- Email: [email protected]
Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction
Accepted Manuscript Title: Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction Authors: Jaehyun Park, Heesung Park PII: DOI: Reference:
S0924-4247(17)31008-7 https://doi.org/10.1016/j.sna.2017.10.044 SNA 10410
To appear in:
Sensors and Actuators A
Received date: Revised date: Accepted date:
30-5-2017 18-9-2017 16-10-2017
Please cite this article as: Jaehyun Park, Heesung Park, Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction, Sensors and Actuators: A Physical https://doi.org/10.1016/j.sna.2017.10.044 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction
IP T
Jaehyun Park, Heesung Park* Department of Mechanical Engineering, Changwon National University, South Korea
U
SC R
Corresponding author Mechanical Engineering Department of Changwon National University, 20 Changwondaehak-ro, Changwon City, 51140 South Korea Telephone: +82-55-213-3609 Email address: [email protected]
M
A
3D-printed thermal cycling device is experimentally studied. The dimensions of the device are 3 x 4 cm with 27 thermal cycles Thermal cycling efficiency is evaluated by the produced temperature zones 3D-printing technology is feasible to microscale thermal cycler.
ED
N
Highlights
PT
Abstract
A polymerase chain reaction (PCR) device with integrated heaters for DNA amplification is proposed by using 3D-printing technology, which has the advantages of fast prototyping,
CC E
design flexibility, and low cost. The thermal characteristics of the 3D-printed device for PCR are reported for the first time. The overall dimensions of the PCR device are 30 mm × 40 mm where a serpentine microchannel is created to implement 27 thermal cycles. The serpentine
A
microchannel of 260 μm in depth, 450 μm in width and 1470 mm in length has been designed to inspect shape conformity and temperature variations. Thermal cycling experiments has showed that three temperature zones for denaturation (90-95 °C), annealing (55-65 °C) and extension (70-77 °C) were successfully produced for DNA amplification. The thermal cycling efficiency ranges 67.4 % to 47.8 % when the flow rate is changed from 5 μL/min to 10 μL/min. The study demonstrates the feasibility of a low-cost 3D-printed PCR device that enables DNA amplification by thermal cycling. This paper concludes that 3D-printing 1
technology can be applied for bio-microfluidic devices that require precise temperature control.
A
CC E
PT
ED
M
A
N
U
SC R
IP T
Keywords: 3D-printer; Microchannel; Polymerase chain reaction; Thermal cycling
2
1. Introduction Polymerase chain reaction (PCR) is a technique for amplifying and detecting DNA. The high sensitivity of PCR enables virus detection soon after infection and even before the onset of disease [1]. Thus, PCR has become one of the most useful and versatile methodologies applied to molecular biological applications [2,3]. With the rapid advance of microfluidic
IP T
technology, miniaturized PCR devices with microchannels have been widely studied [1,4-6] to employ the advantages of the inherent high surface-to-volume ratio, low reagent
consumption, high biochemical reaction speed, and effective energy consumption. Because
SC R
PCR is implemented by the thermal cycling of samples through three temperature steps of denaturation, annealing, and extension [7,8], materials with low thermal conductivity are
favourable for PCR devices [8]. The material used for fabricating the PCR devices is one of the significant factors in terms of heat transfer, fluid flow, manufacturability, and cost. Thus,
U
polyimide [8], PMMA [9], PDMS [10], and polycarbonate [11] have been widely utilized for
N
PCR devices. When using these materials, most PCR devices are fabricated by chemical
A
etching [12], lithography [4], milling [11], and by using microfluidic compact discs [13]. Although these fabrication techniques provide dimensional accuracy and uniform
M
microchannels, limitations persist: in terms of cost, flexibility of design, and fabrication time. Rapid-prototyping, in particular 3D-printing, is a cost-effective and swift alternative [14].
ED
Recently, commercially-available 3D-printers for microfluidic devices are capable of printing to a resolution of 16 μm with a range of polymeric materials [14]. In addition, an increasing
PT
amount of research has been conducted in terms of the resolution [15-17], interconnection [18,19], biocompatibility [20-23], and cost [24,25]. Although Mulberry et al. [26] reported
CC E
that the use of the 3D-printer allowed for complex components to be made in a rapid and low-cost fashion which opens access to PCR device as well as future medical devices; however, they used the 3D-printer to manufacture auxiliary parts of enclosures and holders that are irrelevant to PCR process. 3D-printed serpentine microchannel where PCR takes
A
place has never been studied. In this work, we introduced a PCR device with serpentine microchannel manufactured by
3D-printing technology which has the advantages of cost effectiveness, design flexibility, and high work speed. The thermal cycling characteristics of the 3D-printed PCR device were experimentally evaluated. Note that the thermal characteristics of a 3D-printed microfluidic device have not been reported until now. In general, the materials used for the 3D-printer 3
have low thermal conductivity and are not adequate for applications that need fast heating or cooling functions; however, PCR techniques require a stable and stepwise temperature control scheme. In this regard, the proof-of-concept to have dimensional conformity and thermal characteristics is significant in relation to the 3D-printed fabrication techniques. The proposed 3D-printed PCR device had 27 thermal cycles with three temperature zones in which denaturation, annealing and extension were implemented. As far as the authors know,
surface morphology and manufacturability of the 3D-printed PCR device.
SC R
Polycarbonate plate with observation window
40 mm Heaters Outlet Annealing z x
Adhesive film
3D-printed PCR device
N
Denaturation
Three heaters
Infra-red camera
(a)
Optical microscope
M
Data acquisition and heater control system
Heater fixture
A
Inlet Syringe pump
U
Extension
30 mm y
IP T
this is the first study to investigate the design features, thermal and fluidic characteristics,
Base plate (b)
ED
Fig. 1 (a) 3D-printed PCR device with three heaters integrated for controlling the temperatures in the annealing, extension, and denaturation zones; (b) An exploded view of the PCR device
PT
with the fixture assembly
2. Experimental
CC E
A schematic diagram of the PCR device with three integrated heaters is shown in Fig. 1 (a). The digital light projection 3D-printer (Miicraft Inc.) used for the experiment a the resolution of 56 μm in the x- and y-directions, while the resolution in the z-direction (printing direction)
A
was 5 μm. The 3D-printer fabricated the PCR device by using a photo-curable resin (70 % acryl and 30 % epoxy) in a layer-by-layer sequence via a computer-aided process. The x, y, and z coordinates are indicated in Fig. 1 (a). A serpentine microchannel of 450 μm in width and 260 μm in depth was created at the top of the PCR device. The total length of the microchannel was 1470 mm, enabling 27 thermal cycles. Inlet and outlet ports were fabricated for making connections with the syringe pump and drainage. The total manufacturing time when using the 3D-printer was 2 h, including the ultra-sonic cleaning 4
process. The overall size of the fabricated PCR device, including inlet and outlet ports, was 30 × 40 mm. A transparent adhesive film was attached to the top-surface of the PCR device to prevent the liquid from escaping outside. The film was coated with black lacquer to obtain the temperature profile by using an infra-red (IR) camera. Three heaters were placed at the backside of the PCR device to produce three temperature zones where denaturation, annealing and extension were implemented for DNA amplifications. The PCR device was
IP T
clamped with a polycarbonate plate by using a fixture to apply constant pressure, as
illustrated in Fig. 1 (b). The polycarbonate plate was manufactured with an observation
window for using an optical microscope and IR camera. The experimental setup consisted of
SC R
a syringe pump, a heater control system, an optical microscope, and a data acquisition system. FC-40 (3M company) liquid was used in the experiment to prevent unwanted evaporation in the microchannel during the thermal cycling test. The boiling point, density, specific heat and
U
viscosity of FC-40 are 165 oC, 1855 kg/m3, 1100 J/(kg oC) and 0.0041 N s/m2, respectively. The FC-40 is commonly used as carrier fluid for PCR [27]. Two different flow rates of 5
N
μL/min and 10 μL/min were applied by using the syringe pump to investigate the effect of
A
flow rate; the resulting times to elapse were 35 and 18 minutes, respectively. After the
M
microchannel was completely filled with liquid, the desired flow rate and temperatures of the heaters were controlled with respect to the anticipated temperature zones. Finally, the
A
CC E
PT
ED
measured temperature distributions were collected by the data acquisition system.
Fig. 2 (a) Cross section of the microchannel in the x-y plane (b) Topography of the microchannel surface in the x-z plane
5
3. Results and discussion The 3D-printed PCR device was cross-sectioned, and the shape of the microchannel was inspected by using an optical microscope, as shown in Fig. 2. It shows good shape conformity with curvature at the corners. The differences between the nominal and measured dimensions are summarized in Table 1. The measured microchannel depth was 13.3 % less than the nominal dimension. This difference was due to the presence of curvature features, which
IP T
reduced the depth, at the corners. The microchannel width exceeded the nominal value by 50 μm because the residual resin caused overcut during discharging and cleaning processes,
resulting in 50 μm less wall thickness than the nominal value. The deviations of the measured
SC R
values were within the range of resolutions of the 3D-printer: 56 μm, 56 μm, and 5 μm in the
x-, y-, and z-directions, respectively. Meanwhile, the measured overall width and length were close to the nominal dimensions. The dimensional variance between different sample PCR
U
devices was less than that of serpentine microchannel in a sample PCR device. This indicated
N
that the 3D-printer used in the study showed good reproducibility. The inspected configurations of the microchannel were sufficiently good for implementing liquid flow and
A
thermal cycling. It should be denoted that the material cost of the PCR device was less than 2
ED
M
US dollars.
Topology at the bottom surface of the microchannel was also investigated by atomic force microscopy as shown in Fig. 2 (b). The inspection area was 15 × 15 μm in the x-z plane. A
PT
bump of a maximum height of 1.7 μm was observed, while the average surface roughness was 207 nm. The bump feature was repeated every 5 μm to 10 μm in the z-direction. The
CC E
periodic feature was created by layer-by-layer sequencing during the 3D-printing process with a step size of 5 μm in the z-direction. The measured dimensional variations showed the good conformity of the geometric configurations; however, the observed periodic bump and
A
surface roughness can induce high pressure drop [28] or absorption of DNA or polymerase at the channel surface. The authors are still conducting research to quantify the impact of the topology of the 3D-printed surface during the PCR process. Nonetheless, the 3D-printed PCR device can be applied to provide the advantages of fast prototyping, design flexibility, and low cost. In this regard, thermal cycling experiments were conducted to further investigate the temperature distributions that enabled DNA amplification. Fig. 3 shows the temperature distributions at the top surface of the PCR device for two 6
different flow rates of 5 μL/min and 10 μL/min. The measured pressure drops were 1.4 and 2.7 kPa for the flow rates of 5 μL/min and 10 μL/min, respectively. The syringe pump used in our experiment was sufficient to supply the flow rates with the pressure drop. In this, a single serpentine channel is suitable and appropriate for the biological application. The thermographic images were captured by the IR camera. It should be denoted that the temperature distributions remained unchanged during the time of each experimentation. The
IP T
temperature variation induced by environmental condition was below 0.5 oC. The position numbers were assigned for a thermal cycle with respect to the positions of the heaters. ℃
5
Outlet
85
4
75
3 7 1
Inlet
65
U
6
SC R
95
55
4
7
3 1
2 (b)
ED
6
M
A
N
2 (a) 5
PT
Fig. 3 Thermographic images captured by the infra-red camera (a) 5 μL/min (b) 10 μL/min
CC E
The distances of positions 1-2, 3-4, and 4-5 were 9 mm, 8 mm, and 10 mm, respectively.
The anticipated lengths for the denaturation, annealing and extension, and zones were 18 mm, 20 mm, and 8 mm, respectively. The thermographic images indicated favourable thermal
A
cycling close to the desired temperature variations from 58 °C to 92 °C along the microchannel length. It should be denoted that the thin cover film (thickness: 100 µm) allowed thermographic analysis of the temperature close to the fluid. Three temperature zones of 90 - 95 °C, 70 - 77 °C and 55 - 65 °C were anticipated for denaturation, extension, and annealing, respectively; in the figure, rectangular boxes represent the positions where PCR occurred for DNA amplification. The integrated heaters and 3D-printed microchannel PCR device produced repetitive temperature variations for each thermal cycle. Although 7
temperature at the edges of the PCR device was affected by natural convection, the temperature zones were well produced to satisfy the thermal requirements in DNA amplification process as shown in Fig. 4. The low temperature resulting from natural convection at positions 2 and 5 mitigated excessive temperature rise during denaturation and annealing. When the flow rate was 5 μL/min, the resulting lengths of denaturation, annealing and extension per thermal cycle were 8 mm, 20 mm, and 3 mm, respectively. In these, the
IP T
estimated fluid residence times were 11 s, 28 s and 4 s for denaturation, annealing and
extension per cycle. In addition, the extension zone had a significant temperature gradient
because of heat transfer from the denaturation and annealing zones. To reduce the thermal
SC R
interference, the gap between the heaters should be optimized. The heat losses on the top and
ED
M
A
N
U
side surfaces were also significant parameters for the temperature distribution at the zones.
PT
Fig. 4 The measured temperature distributions for two flow rates 5 μL/min and 10 μL/min
To avoid natural convective heat loss, thermal insulation design should be carefully
CC E
considered. The high flow rate of 10 μL/min provided a more extended temperature zone of 13 mm for denaturation while the annealing zone was considerably reduced to 6 mm. This is attributed to the enhanced convective heat transfer inside the microchannel. In these, the
A
estimated fluid residence times were 9 s, 4 s and 2 s for denaturation, annealing and extension per cycle. Although high flow rate of 10 μL/min offered more heat transfer from heaters, it adversely affected the residence time. Therefore, one should compromise the heat transfer characteristic in accordance with the flow rate as well as channel dimension. If we define the thermal cycling efficiency as described in equation (1), the resulting efficiency varies from 67.4 % to 47.8 % when the flow rate is changed from 5 μL/min to 10 μL/min. The proposed 8
equation (1) can be utilized to evaluate and discriminate between the thermal cycling efficiency and DNA amplification. It is noted that Ltotal represents the total length for thermal cycling, while Ldenaturation, Lextension, and Lannealing represent the lengths of the denaturation, extension, and annealing zones, respectively. Although the biological reaction characteristics of a DNA sample determines the time of thermal cycling, temperature zones, and flow rate, the proposed thermal cycling efficiency can be useful to evaluate the performance before
IP T
conducting DNA amplification by using real samples. Therefore, one can figure out the impact of thermal cycling through PCR process. ∑{𝐿𝑎𝑛𝑛𝑒𝑎𝑙𝑖𝑛𝑔 +𝐿𝑒𝑥𝑡𝑒𝑛𝑠𝑖𝑜𝑛 +𝐿𝑑𝑒𝑛𝑎𝑡𝑢𝑟𝑎𝑡𝑖𝑜𝑛 }
SC R
η𝑡ℎ𝑒𝑟𝑚𝑎𝑙 =
𝑇𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑓𝑜𝑟 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑦𝑐𝑙𝑖𝑛𝑔
(1)
The biocompatibility, thermal deformation, shape conformity, and thermal conductivity of
U
material are still significant factors to be considered to further enhance the PCR device
N
manufactured by the 3D-printer. The authors are still investigating the optimum design
A
parameters considering the material characteristics for a 3D-printed PCR device.
M
4. Conclusions
In this study, a low-cost and 3D-printed PCR device with integrated heaters was introduced.
ED
A serpentine microchannel (width: 450 μm, depth: 260 μm, and total length: 1470 mm) was created at the top surface of the PCR device. This microchannel enabled 27 thermal cycles for
PT
DNA amplification. Although spatial discrepancy, high surface roughness, and periodic bumps were observed at the microchannel surface, the 3D-printed microchannel yielded good
CC E
shape conformity for application in the PCR process. The IR thermographic images indicated that the three temperature zones were successfully produced by the proposed 3D-printed PCR device. It was also found that the increased flow rate enhanced the convective heat transfer, resulting in a more uniform temperature distribution than that achieved at a lower flow rate.
A
Although the heat loss due to natural convection is still significant during thermal cycling, it can be controlled by thermal insulation design. With the proposed thermal cycling efficiency, a more sophisticated design and temperature control strategy should be applied to achieve effective DNA amplification. Future works should be conducted to optimize the material characteristics, surface morphology, heater array, thermal and microfluidic design parameters for the biocompatible and reliable 3D-printed PCR device. Furthermore, an actual 9
amplification efficiency needs to be reported by using real DNA samples to characterize the performance of 3D-printed PCR device.
Acknowledgement This research was supported by the Basic Science Research Program through the National
IP T
Research Foundation of Korea (NRF) funded by the Ministry of Education (No.
2015R1D1A3A01019588). This research was also financially supported by the Ministry of
Project for Regional Innovation (No. 2015H1C1A1035824).
References
J. Wu, R. Kodzius, W. Cao, W. Wen, Extraction, amplification and detection of DNA in
U
[1]
SC R
Education and National Research Foundation of Korea through the Human Resource Training
[2]
N
microfluidic chip-based assays, Microchim Acta 181 (2014) 1611-1631. Y. Liu, J.X. Han, H.Y. Huang, B. Zhu, Development and evaluation of 16S rDNA
A
microarray for detecting bacterial pathogens in cerebrospinal fluid, Exp. Biol. Med. 230
[3]
M
(2005) 587-591.
K. Sen, D.M. Asher, Multiplex PCR for detection of enterobacteriaceae in blood,
[4]
ED
Transfusion 41 (2001) 1356-1364.
X. Jiang, N. Shao, W. Jing, S. Tao, S. Liu, G. Sui, Microfluidic chip integrating high throughput continuous-flow PCR and DNA hybridization for bacteria analysis, Talanta
[5]
PT
122 (2014) 246-250.
Y. Zhu, Y.X. Zhang, W.W. Liu, Y. Ma, Q. Fang, B. Yao, Printing 2-dimentional droplet
CC E
array for single-cell reverse transcription quantitative PCR assay with a microfluidic robot, Nature, Scientific reports 5 (2015) 9551.
[6]
A. Zahra, R. Scipinotti, D. Caputo, A. Nascetti, G. de Cesare, Design and fabrication of
A
microfluidics system integrated with temperature actuated microvalve, Sens. Actuators A 236 (2015) 206-213.
[7]
C.D. Ahrberg, A. Manz, B.G. Chung, Polymerase chain reaction in microfluidic devices, Lap chip 16 (2016) 3866-3884.
[8]
D. Moschou, N. Vourdas, G. Kokkoris, G. Papadakis, J. Parthenios, S. Chatzandroulis, A. Tserepi, All-plastic, low-power, disposable, continuous-flow PCR chip with integrated microheaters for rapid DNA amplification, Sens. Actuators B 199 (2014) 47010
478. [9]
Y. Sun, M.V.D. Satyanarayan, N.T. Nguyen, Y.C. Kwok, Continuous flow polymerase chain reaction using a hybrid PMMA-PC microchip with improved heat tolerance, Sens. Actuators B 130 (2008) 836-841.
[10]
A.R. Prakash, S. Adamia, V. Sieben, P. Pilarski, L.M. Pilarski, C.J. Backhouse, Small volume PCR in PDMS biochips with integrated fluid control and vapour barrier, Sens.
[11]
IP T
Actuators B 133 (2006) 398-409.
M.L. Ha, N.Y. Lee, Miniaturized polymerase chain reaction device for rapid
identification of genetically modified organisms, Food Control 57 (2015) 238-245.
H. Tachibana, M. Saito, K. Tsuji, K. Yamanaka, L.Q. Hoa, E. Tamiya, Self-propelled
SC R
[12]
continuous-flow PCR in capillary-driven microfluidic device: Microfluidic behavior and DNA amplification, Sens. Actuators B 206 (2015) 303-310.
K. Joseph, F. Ibrahim, J. Cho, T.H.G. Thio, W. Al-Faqheri, M. Madou, Design and
U
[13]
N
development of micro-power generating device for biomedical application of lab-on-adisc, Plos one, 2015. http://dx.doi.org/10.1371/journal.pone.0136519. J. O’Connor, J. Punch, N. Jeffers, J. Stafford, A dimensional comparison between
A
[14]
[15]
M
embedded 3D-printed and silicon microchannels, J. of Physics 525 (2014) 012009. J.C. McDonald, G.M. Whitesides, Poly(dimethylsiloxane) as a material for fabricating
[16]
ED
microfluidic devices, Anal. Chem. 35 (2002) 491-499. C.C. Glick, M.T. Srimongkol, A.J. Schwarz, W.S. Zhuang, J.C. Lin, R.H. Warren, D.R. Tekell, P.A. Satamalee, L. Lin, Rapid assembly of multilayer microfluidic structures via
16063.
A.I. Shallan, P. Smejkal, M. Corban, R.M. Guijt, M.C. Breadmore, Cost-effective three-
CC E
[17]
PT
3D-printed transfer molding and bonding, Microsystems & Nanoengineering 2 (2016)
dimensional printing of visibly transparent microchips within minutes, Anal. Chem. 86 (2014) 3124-3130. K.C. Bhargava, B. Thompson, N. Malmstadt, Discrete elements for 3D microfluidics,
A
[18]
Pnas 111 (2014) 15015-15018.
[19]
O.H. Paydar, C.N. Paredes, Y. Hwang, J. Paz, N.B. Shah, R.N. Candler, Characterization of 3D-printed microfluidic chip interconnects with integrated o-rings, Sens. Actuators A 205 (2014) 199-203.
[20]
E.J. McCullough, V.K. Yadavalli, Surface modification of fused deposition modelling ABS to enable rapid prototyping of biomedical microdevices, J. Materials Processing 11
Tech. 213 (2013) 947-954. [21]
P.H. King, Towards rapid 3D direct manufacture of biomechanical microstructures (Ph.D. thesis), University of Warwick, 2009.
[22]
M.M. Stanton, J. Samitier, S. Sánchez, Bioprinting of 3D hydrogels, Lap chip 15 (2015) 3111-3115. C.I. Rogers, K. Qaderi, A.T. Woolley, G.P. Nordin, 3D printed microfluidic devices with integrated valves, Biomicrofluidics 9 (2015) 016501.
[24]
IP T
[23]
J.L. Moore, A. McCuiston, I. Mittendorf, R. Ottway, R.D. Johnson, Behavior of
capillary valves in centrifugal microfluidic devices prepared by three-dimensional
[25]
SC R
printing, Microfluidics and Nanofluidics 10 (2011) 877-888.
A. Bonyár, H. Sántha, B. Ring, M. Varga, J.G. Kovács, G. Harsányi, 3D rapid prototyping technology (RPT) as a powerful tool in microfluidics development, Procedia
G. Mulberry G, K. A. White, M. Vaidya, K. Sugaya, B. N. Kim, 3D printing and milling
N
[26]
U
Engineering 5 (2010) 291-294.
a real-time PCR device for infectious disease diagnostics, PLoS ONE 12 (2017)
A. C. Hatch, T. Ray, K. Lintecum, C. Youngbull, Continuous flow real-time PCR device
M
[27]
A
e0179133.
using multi-channel fluorescence excitation and detection, Lab on a Chip 14 (2014) 562-
[28]
ED
568.
H. Park, S. H. Choa, Measurement of liquid flow rate by self-generated electrokinetic
CC E
Biography
PT
potential on the microchannel surface of a solid, Sens. Actuators A 208 (2014) 88-94.
Professor Heesung Park is currently Associate Professor in Mechanical Engineering Department, Changwon National University, South Korea. His research area extends to
A
sustainable and renewable batteries, biomedical microfluidic devices, and small scale turboimpellers. He earned his PhD from Yonsei University in South Korea examining microfluidic and electrostatic phenomena in 2003. He then joined Digital Media R&D Center of Samsung Electronics as a Senior Researcher. From 2006, he joined Stokes Institute in University of Limerick, Ireland to undertake research project of microscale cooling as a principal investigator. He also has experience at Fuel Cell Electric Vehicle Team in Hyundai Motor Company from 2008 to 2014. He is supervising 2 PhD and 3 MS students in his Nanoscale 12
Thermo-fluidics and Energy Transfer Laboratory. He has published over 50 refereed papers and hold 12 patents. Mr. Jaehyun Park’s research interests are the fluid mechanics and heat transfer in application area of 3D-printed micro fluidic devices. He is currently PhD candidate in Graduate School of Mechanical Engineering at Changwon National University, South Korea. Mr. Park has a
IP T
BEng in Mechanical Engineering awarded in 2013 and his MEng, awarded from the Changwon National University in 2015. He has interested in optical techniques for
measurement at the microscale and dimensional analysis in heat transfer and fluid mechanics.
SC R
At present, the primary application of his work is in the development of bio-microfluidic systems.
Microchannel 300 400 200
PCR device
29600 39700 640
PT
30000 40000 700
Variance (%)
Minimum
271.7 474.4 165.2
252.6 434.5 135.8
13.3 11.1 25
648.4
637.2
0.8 1.3 8.6
A
CC E
Width Length Thickness
260 450 150
ED
Depth Width Wall
Maximum
M
Average
N
Measured (μm)
A
Nominal (μm)
U
Table 1 Comparison of the nominal and measured dimensions of the 3D-printed PCR device
13
S0924-4247(17)31008-7 https://doi.org/10.1016/j.sna.2017.10.044 SNA 10410
To appear in:
Sensors and Actuators A
Received date: Revised date: Accepted date:
30-5-2017 18-9-2017 16-10-2017
Please cite this article as: Jaehyun Park, Heesung Park, Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction, Sensors and Actuators: A Physical https://doi.org/10.1016/j.sna.2017.10.044 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Thermal cycling characteristics of a 3D-printed serpentine microchannel for DNA amplification by polymerase chain reaction
IP T
Jaehyun Park, Heesung Park* Department of Mechanical Engineering, Changwon National University, South Korea
U
SC R
Corresponding author Mechanical Engineering Department of Changwon National University, 20 Changwondaehak-ro, Changwon City, 51140 South Korea Telephone: +82-55-213-3609 Email address: [email protected]
M
A
3D-printed thermal cycling device is experimentally studied. The dimensions of the device are 3 x 4 cm with 27 thermal cycles Thermal cycling efficiency is evaluated by the produced temperature zones 3D-printing technology is feasible to microscale thermal cycler.
ED
N
Highlights
PT
Abstract
A polymerase chain reaction (PCR) device with integrated heaters for DNA amplification is proposed by using 3D-printing technology, which has the advantages of fast prototyping,
CC E
design flexibility, and low cost. The thermal characteristics of the 3D-printed device for PCR are reported for the first time. The overall dimensions of the PCR device are 30 mm × 40 mm where a serpentine microchannel is created to implement 27 thermal cycles. The serpentine
A
microchannel of 260 μm in depth, 450 μm in width and 1470 mm in length has been designed to inspect shape conformity and temperature variations. Thermal cycling experiments has showed that three temperature zones for denaturation (90-95 °C), annealing (55-65 °C) and extension (70-77 °C) were successfully produced for DNA amplification. The thermal cycling efficiency ranges 67.4 % to 47.8 % when the flow rate is changed from 5 μL/min to 10 μL/min. The study demonstrates the feasibility of a low-cost 3D-printed PCR device that enables DNA amplification by thermal cycling. This paper concludes that 3D-printing 1
technology can be applied for bio-microfluidic devices that require precise temperature control.
A
CC E
PT
ED
M
A
N
U
SC R
IP T
Keywords: 3D-printer; Microchannel; Polymerase chain reaction; Thermal cycling
2
1. Introduction Polymerase chain reaction (PCR) is a technique for amplifying and detecting DNA. The high sensitivity of PCR enables virus detection soon after infection and even before the onset of disease [1]. Thus, PCR has become one of the most useful and versatile methodologies applied to molecular biological applications [2,3]. With the rapid advance of microfluidic
IP T
technology, miniaturized PCR devices with microchannels have been widely studied [1,4-6] to employ the advantages of the inherent high surface-to-volume ratio, low reagent
consumption, high biochemical reaction speed, and effective energy consumption. Because
SC R
PCR is implemented by the thermal cycling of samples through three temperature steps of denaturation, annealing, and extension [7,8], materials with low thermal conductivity are
favourable for PCR devices [8]. The material used for fabricating the PCR devices is one of the significant factors in terms of heat transfer, fluid flow, manufacturability, and cost. Thus,
U
polyimide [8], PMMA [9], PDMS [10], and polycarbonate [11] have been widely utilized for
N
PCR devices. When using these materials, most PCR devices are fabricated by chemical
A
etching [12], lithography [4], milling [11], and by using microfluidic compact discs [13]. Although these fabrication techniques provide dimensional accuracy and uniform
M
microchannels, limitations persist: in terms of cost, flexibility of design, and fabrication time. Rapid-prototyping, in particular 3D-printing, is a cost-effective and swift alternative [14].
ED
Recently, commercially-available 3D-printers for microfluidic devices are capable of printing to a resolution of 16 μm with a range of polymeric materials [14]. In addition, an increasing
PT
amount of research has been conducted in terms of the resolution [15-17], interconnection [18,19], biocompatibility [20-23], and cost [24,25]. Although Mulberry et al. [26] reported
CC E
that the use of the 3D-printer allowed for complex components to be made in a rapid and low-cost fashion which opens access to PCR device as well as future medical devices; however, they used the 3D-printer to manufacture auxiliary parts of enclosures and holders that are irrelevant to PCR process. 3D-printed serpentine microchannel where PCR takes
A
place has never been studied. In this work, we introduced a PCR device with serpentine microchannel manufactured by
3D-printing technology which has the advantages of cost effectiveness, design flexibility, and high work speed. The thermal cycling characteristics of the 3D-printed PCR device were experimentally evaluated. Note that the thermal characteristics of a 3D-printed microfluidic device have not been reported until now. In general, the materials used for the 3D-printer 3
have low thermal conductivity and are not adequate for applications that need fast heating or cooling functions; however, PCR techniques require a stable and stepwise temperature control scheme. In this regard, the proof-of-concept to have dimensional conformity and thermal characteristics is significant in relation to the 3D-printed fabrication techniques. The proposed 3D-printed PCR device had 27 thermal cycles with three temperature zones in which denaturation, annealing and extension were implemented. As far as the authors know,
surface morphology and manufacturability of the 3D-printed PCR device.
SC R
Polycarbonate plate with observation window
40 mm Heaters Outlet Annealing z x
Adhesive film
3D-printed PCR device
N
Denaturation
Three heaters
Infra-red camera
(a)
Optical microscope
M
Data acquisition and heater control system
Heater fixture
A
Inlet Syringe pump
U
Extension
30 mm y
IP T
this is the first study to investigate the design features, thermal and fluidic characteristics,
Base plate (b)
ED
Fig. 1 (a) 3D-printed PCR device with three heaters integrated for controlling the temperatures in the annealing, extension, and denaturation zones; (b) An exploded view of the PCR device
PT
with the fixture assembly
2. Experimental
CC E
A schematic diagram of the PCR device with three integrated heaters is shown in Fig. 1 (a). The digital light projection 3D-printer (Miicraft Inc.) used for the experiment a the resolution of 56 μm in the x- and y-directions, while the resolution in the z-direction (printing direction)
A
was 5 μm. The 3D-printer fabricated the PCR device by using a photo-curable resin (70 % acryl and 30 % epoxy) in a layer-by-layer sequence via a computer-aided process. The x, y, and z coordinates are indicated in Fig. 1 (a). A serpentine microchannel of 450 μm in width and 260 μm in depth was created at the top of the PCR device. The total length of the microchannel was 1470 mm, enabling 27 thermal cycles. Inlet and outlet ports were fabricated for making connections with the syringe pump and drainage. The total manufacturing time when using the 3D-printer was 2 h, including the ultra-sonic cleaning 4
process. The overall size of the fabricated PCR device, including inlet and outlet ports, was 30 × 40 mm. A transparent adhesive film was attached to the top-surface of the PCR device to prevent the liquid from escaping outside. The film was coated with black lacquer to obtain the temperature profile by using an infra-red (IR) camera. Three heaters were placed at the backside of the PCR device to produce three temperature zones where denaturation, annealing and extension were implemented for DNA amplifications. The PCR device was
IP T
clamped with a polycarbonate plate by using a fixture to apply constant pressure, as
illustrated in Fig. 1 (b). The polycarbonate plate was manufactured with an observation
window for using an optical microscope and IR camera. The experimental setup consisted of
SC R
a syringe pump, a heater control system, an optical microscope, and a data acquisition system. FC-40 (3M company) liquid was used in the experiment to prevent unwanted evaporation in the microchannel during the thermal cycling test. The boiling point, density, specific heat and
U
viscosity of FC-40 are 165 oC, 1855 kg/m3, 1100 J/(kg oC) and 0.0041 N s/m2, respectively. The FC-40 is commonly used as carrier fluid for PCR [27]. Two different flow rates of 5
N
μL/min and 10 μL/min were applied by using the syringe pump to investigate the effect of
A
flow rate; the resulting times to elapse were 35 and 18 minutes, respectively. After the
M
microchannel was completely filled with liquid, the desired flow rate and temperatures of the heaters were controlled with respect to the anticipated temperature zones. Finally, the
A
CC E
PT
ED
measured temperature distributions were collected by the data acquisition system.
Fig. 2 (a) Cross section of the microchannel in the x-y plane (b) Topography of the microchannel surface in the x-z plane
5
3. Results and discussion The 3D-printed PCR device was cross-sectioned, and the shape of the microchannel was inspected by using an optical microscope, as shown in Fig. 2. It shows good shape conformity with curvature at the corners. The differences between the nominal and measured dimensions are summarized in Table 1. The measured microchannel depth was 13.3 % less than the nominal dimension. This difference was due to the presence of curvature features, which
IP T
reduced the depth, at the corners. The microchannel width exceeded the nominal value by 50 μm because the residual resin caused overcut during discharging and cleaning processes,
resulting in 50 μm less wall thickness than the nominal value. The deviations of the measured
SC R
values were within the range of resolutions of the 3D-printer: 56 μm, 56 μm, and 5 μm in the
x-, y-, and z-directions, respectively. Meanwhile, the measured overall width and length were close to the nominal dimensions. The dimensional variance between different sample PCR
U
devices was less than that of serpentine microchannel in a sample PCR device. This indicated
N
that the 3D-printer used in the study showed good reproducibility. The inspected configurations of the microchannel were sufficiently good for implementing liquid flow and
A
thermal cycling. It should be denoted that the material cost of the PCR device was less than 2
ED
M
US dollars.
Topology at the bottom surface of the microchannel was also investigated by atomic force microscopy as shown in Fig. 2 (b). The inspection area was 15 × 15 μm in the x-z plane. A
PT
bump of a maximum height of 1.7 μm was observed, while the average surface roughness was 207 nm. The bump feature was repeated every 5 μm to 10 μm in the z-direction. The
CC E
periodic feature was created by layer-by-layer sequencing during the 3D-printing process with a step size of 5 μm in the z-direction. The measured dimensional variations showed the good conformity of the geometric configurations; however, the observed periodic bump and
A
surface roughness can induce high pressure drop [28] or absorption of DNA or polymerase at the channel surface. The authors are still conducting research to quantify the impact of the topology of the 3D-printed surface during the PCR process. Nonetheless, the 3D-printed PCR device can be applied to provide the advantages of fast prototyping, design flexibility, and low cost. In this regard, thermal cycling experiments were conducted to further investigate the temperature distributions that enabled DNA amplification. Fig. 3 shows the temperature distributions at the top surface of the PCR device for two 6
different flow rates of 5 μL/min and 10 μL/min. The measured pressure drops were 1.4 and 2.7 kPa for the flow rates of 5 μL/min and 10 μL/min, respectively. The syringe pump used in our experiment was sufficient to supply the flow rates with the pressure drop. In this, a single serpentine channel is suitable and appropriate for the biological application. The thermographic images were captured by the IR camera. It should be denoted that the temperature distributions remained unchanged during the time of each experimentation. The
IP T
temperature variation induced by environmental condition was below 0.5 oC. The position numbers were assigned for a thermal cycle with respect to the positions of the heaters. ℃
5
Outlet
85
4
75
3 7 1
Inlet
65
U
6
SC R
95
55
4
7
3 1
2 (b)
ED
6
M
A
N
2 (a) 5
PT
Fig. 3 Thermographic images captured by the infra-red camera (a) 5 μL/min (b) 10 μL/min
CC E
The distances of positions 1-2, 3-4, and 4-5 were 9 mm, 8 mm, and 10 mm, respectively.
The anticipated lengths for the denaturation, annealing and extension, and zones were 18 mm, 20 mm, and 8 mm, respectively. The thermographic images indicated favourable thermal
A
cycling close to the desired temperature variations from 58 °C to 92 °C along the microchannel length. It should be denoted that the thin cover film (thickness: 100 µm) allowed thermographic analysis of the temperature close to the fluid. Three temperature zones of 90 - 95 °C, 70 - 77 °C and 55 - 65 °C were anticipated for denaturation, extension, and annealing, respectively; in the figure, rectangular boxes represent the positions where PCR occurred for DNA amplification. The integrated heaters and 3D-printed microchannel PCR device produced repetitive temperature variations for each thermal cycle. Although 7
temperature at the edges of the PCR device was affected by natural convection, the temperature zones were well produced to satisfy the thermal requirements in DNA amplification process as shown in Fig. 4. The low temperature resulting from natural convection at positions 2 and 5 mitigated excessive temperature rise during denaturation and annealing. When the flow rate was 5 μL/min, the resulting lengths of denaturation, annealing and extension per thermal cycle were 8 mm, 20 mm, and 3 mm, respectively. In these, the
IP T
estimated fluid residence times were 11 s, 28 s and 4 s for denaturation, annealing and
extension per cycle. In addition, the extension zone had a significant temperature gradient
because of heat transfer from the denaturation and annealing zones. To reduce the thermal
SC R
interference, the gap between the heaters should be optimized. The heat losses on the top and
ED
M
A
N
U
side surfaces were also significant parameters for the temperature distribution at the zones.
PT
Fig. 4 The measured temperature distributions for two flow rates 5 μL/min and 10 μL/min
To avoid natural convective heat loss, thermal insulation design should be carefully
CC E
considered. The high flow rate of 10 μL/min provided a more extended temperature zone of 13 mm for denaturation while the annealing zone was considerably reduced to 6 mm. This is attributed to the enhanced convective heat transfer inside the microchannel. In these, the
A
estimated fluid residence times were 9 s, 4 s and 2 s for denaturation, annealing and extension per cycle. Although high flow rate of 10 μL/min offered more heat transfer from heaters, it adversely affected the residence time. Therefore, one should compromise the heat transfer characteristic in accordance with the flow rate as well as channel dimension. If we define the thermal cycling efficiency as described in equation (1), the resulting efficiency varies from 67.4 % to 47.8 % when the flow rate is changed from 5 μL/min to 10 μL/min. The proposed 8
equation (1) can be utilized to evaluate and discriminate between the thermal cycling efficiency and DNA amplification. It is noted that Ltotal represents the total length for thermal cycling, while Ldenaturation, Lextension, and Lannealing represent the lengths of the denaturation, extension, and annealing zones, respectively. Although the biological reaction characteristics of a DNA sample determines the time of thermal cycling, temperature zones, and flow rate, the proposed thermal cycling efficiency can be useful to evaluate the performance before
IP T
conducting DNA amplification by using real samples. Therefore, one can figure out the impact of thermal cycling through PCR process. ∑{𝐿𝑎𝑛𝑛𝑒𝑎𝑙𝑖𝑛𝑔 +𝐿𝑒𝑥𝑡𝑒𝑛𝑠𝑖𝑜𝑛 +𝐿𝑑𝑒𝑛𝑎𝑡𝑢𝑟𝑎𝑡𝑖𝑜𝑛 }
SC R
η𝑡ℎ𝑒𝑟𝑚𝑎𝑙 =
𝑇𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑓𝑜𝑟 𝑡ℎ𝑒𝑟𝑚𝑎𝑙 𝑐𝑦𝑐𝑙𝑖𝑛𝑔
(1)
The biocompatibility, thermal deformation, shape conformity, and thermal conductivity of
U
material are still significant factors to be considered to further enhance the PCR device
N
manufactured by the 3D-printer. The authors are still investigating the optimum design
A
parameters considering the material characteristics for a 3D-printed PCR device.
M
4. Conclusions
In this study, a low-cost and 3D-printed PCR device with integrated heaters was introduced.
ED
A serpentine microchannel (width: 450 μm, depth: 260 μm, and total length: 1470 mm) was created at the top surface of the PCR device. This microchannel enabled 27 thermal cycles for
PT
DNA amplification. Although spatial discrepancy, high surface roughness, and periodic bumps were observed at the microchannel surface, the 3D-printed microchannel yielded good
CC E
shape conformity for application in the PCR process. The IR thermographic images indicated that the three temperature zones were successfully produced by the proposed 3D-printed PCR device. It was also found that the increased flow rate enhanced the convective heat transfer, resulting in a more uniform temperature distribution than that achieved at a lower flow rate.
A
Although the heat loss due to natural convection is still significant during thermal cycling, it can be controlled by thermal insulation design. With the proposed thermal cycling efficiency, a more sophisticated design and temperature control strategy should be applied to achieve effective DNA amplification. Future works should be conducted to optimize the material characteristics, surface morphology, heater array, thermal and microfluidic design parameters for the biocompatible and reliable 3D-printed PCR device. Furthermore, an actual 9
amplification efficiency needs to be reported by using real DNA samples to characterize the performance of 3D-printed PCR device.
Acknowledgement This research was supported by the Basic Science Research Program through the National
IP T
Research Foundation of Korea (NRF) funded by the Ministry of Education (No.
2015R1D1A3A01019588). This research was also financially supported by the Ministry of
Project for Regional Innovation (No. 2015H1C1A1035824).
References
J. Wu, R. Kodzius, W. Cao, W. Wen, Extraction, amplification and detection of DNA in
U
[1]
SC R
Education and National Research Foundation of Korea through the Human Resource Training
[2]
N
microfluidic chip-based assays, Microchim Acta 181 (2014) 1611-1631. Y. Liu, J.X. Han, H.Y. Huang, B. Zhu, Development and evaluation of 16S rDNA
A
microarray for detecting bacterial pathogens in cerebrospinal fluid, Exp. Biol. Med. 230
[3]
M
(2005) 587-591.
K. Sen, D.M. Asher, Multiplex PCR for detection of enterobacteriaceae in blood,
[4]
ED
Transfusion 41 (2001) 1356-1364.
X. Jiang, N. Shao, W. Jing, S. Tao, S. Liu, G. Sui, Microfluidic chip integrating high throughput continuous-flow PCR and DNA hybridization for bacteria analysis, Talanta
[5]
PT
122 (2014) 246-250.
Y. Zhu, Y.X. Zhang, W.W. Liu, Y. Ma, Q. Fang, B. Yao, Printing 2-dimentional droplet
CC E
array for single-cell reverse transcription quantitative PCR assay with a microfluidic robot, Nature, Scientific reports 5 (2015) 9551.
[6]
A. Zahra, R. Scipinotti, D. Caputo, A. Nascetti, G. de Cesare, Design and fabrication of
A
microfluidics system integrated with temperature actuated microvalve, Sens. Actuators A 236 (2015) 206-213.
[7]
C.D. Ahrberg, A. Manz, B.G. Chung, Polymerase chain reaction in microfluidic devices, Lap chip 16 (2016) 3866-3884.
[8]
D. Moschou, N. Vourdas, G. Kokkoris, G. Papadakis, J. Parthenios, S. Chatzandroulis, A. Tserepi, All-plastic, low-power, disposable, continuous-flow PCR chip with integrated microheaters for rapid DNA amplification, Sens. Actuators B 199 (2014) 47010
478. [9]
Y. Sun, M.V.D. Satyanarayan, N.T. Nguyen, Y.C. Kwok, Continuous flow polymerase chain reaction using a hybrid PMMA-PC microchip with improved heat tolerance, Sens. Actuators B 130 (2008) 836-841.
[10]
A.R. Prakash, S. Adamia, V. Sieben, P. Pilarski, L.M. Pilarski, C.J. Backhouse, Small volume PCR in PDMS biochips with integrated fluid control and vapour barrier, Sens.
[11]
IP T
Actuators B 133 (2006) 398-409.
M.L. Ha, N.Y. Lee, Miniaturized polymerase chain reaction device for rapid
identification of genetically modified organisms, Food Control 57 (2015) 238-245.
H. Tachibana, M. Saito, K. Tsuji, K. Yamanaka, L.Q. Hoa, E. Tamiya, Self-propelled
SC R
[12]
continuous-flow PCR in capillary-driven microfluidic device: Microfluidic behavior and DNA amplification, Sens. Actuators B 206 (2015) 303-310.
K. Joseph, F. Ibrahim, J. Cho, T.H.G. Thio, W. Al-Faqheri, M. Madou, Design and
U
[13]
N
development of micro-power generating device for biomedical application of lab-on-adisc, Plos one, 2015. http://dx.doi.org/10.1371/journal.pone.0136519. J. O’Connor, J. Punch, N. Jeffers, J. Stafford, A dimensional comparison between
A
[14]
[15]
M
embedded 3D-printed and silicon microchannels, J. of Physics 525 (2014) 012009. J.C. McDonald, G.M. Whitesides, Poly(dimethylsiloxane) as a material for fabricating
[16]
ED
microfluidic devices, Anal. Chem. 35 (2002) 491-499. C.C. Glick, M.T. Srimongkol, A.J. Schwarz, W.S. Zhuang, J.C. Lin, R.H. Warren, D.R. Tekell, P.A. Satamalee, L. Lin, Rapid assembly of multilayer microfluidic structures via
16063.
A.I. Shallan, P. Smejkal, M. Corban, R.M. Guijt, M.C. Breadmore, Cost-effective three-
CC E
[17]
PT
3D-printed transfer molding and bonding, Microsystems & Nanoengineering 2 (2016)
dimensional printing of visibly transparent microchips within minutes, Anal. Chem. 86 (2014) 3124-3130. K.C. Bhargava, B. Thompson, N. Malmstadt, Discrete elements for 3D microfluidics,
A
[18]
Pnas 111 (2014) 15015-15018.
[19]
O.H. Paydar, C.N. Paredes, Y. Hwang, J. Paz, N.B. Shah, R.N. Candler, Characterization of 3D-printed microfluidic chip interconnects with integrated o-rings, Sens. Actuators A 205 (2014) 199-203.
[20]
E.J. McCullough, V.K. Yadavalli, Surface modification of fused deposition modelling ABS to enable rapid prototyping of biomedical microdevices, J. Materials Processing 11
Tech. 213 (2013) 947-954. [21]
P.H. King, Towards rapid 3D direct manufacture of biomechanical microstructures (Ph.D. thesis), University of Warwick, 2009.
[22]
M.M. Stanton, J. Samitier, S. Sánchez, Bioprinting of 3D hydrogels, Lap chip 15 (2015) 3111-3115. C.I. Rogers, K. Qaderi, A.T. Woolley, G.P. Nordin, 3D printed microfluidic devices with integrated valves, Biomicrofluidics 9 (2015) 016501.
[24]
IP T
[23]
J.L. Moore, A. McCuiston, I. Mittendorf, R. Ottway, R.D. Johnson, Behavior of
capillary valves in centrifugal microfluidic devices prepared by three-dimensional
[25]
SC R
printing, Microfluidics and Nanofluidics 10 (2011) 877-888.
A. Bonyár, H. Sántha, B. Ring, M. Varga, J.G. Kovács, G. Harsányi, 3D rapid prototyping technology (RPT) as a powerful tool in microfluidics development, Procedia
G. Mulberry G, K. A. White, M. Vaidya, K. Sugaya, B. N. Kim, 3D printing and milling
N
[26]
U
Engineering 5 (2010) 291-294.
a real-time PCR device for infectious disease diagnostics, PLoS ONE 12 (2017)
A. C. Hatch, T. Ray, K. Lintecum, C. Youngbull, Continuous flow real-time PCR device
M
[27]
A
e0179133.
using multi-channel fluorescence excitation and detection, Lab on a Chip 14 (2014) 562-
[28]
ED
568.
H. Park, S. H. Choa, Measurement of liquid flow rate by self-generated electrokinetic
CC E
Biography
PT
potential on the microchannel surface of a solid, Sens. Actuators A 208 (2014) 88-94.
Professor Heesung Park is currently Associate Professor in Mechanical Engineering Department, Changwon National University, South Korea. His research area extends to
A
sustainable and renewable batteries, biomedical microfluidic devices, and small scale turboimpellers. He earned his PhD from Yonsei University in South Korea examining microfluidic and electrostatic phenomena in 2003. He then joined Digital Media R&D Center of Samsung Electronics as a Senior Researcher. From 2006, he joined Stokes Institute in University of Limerick, Ireland to undertake research project of microscale cooling as a principal investigator. He also has experience at Fuel Cell Electric Vehicle Team in Hyundai Motor Company from 2008 to 2014. He is supervising 2 PhD and 3 MS students in his Nanoscale 12
Thermo-fluidics and Energy Transfer Laboratory. He has published over 50 refereed papers and hold 12 patents. Mr. Jaehyun Park’s research interests are the fluid mechanics and heat transfer in application area of 3D-printed micro fluidic devices. He is currently PhD candidate in Graduate School of Mechanical Engineering at Changwon National University, South Korea. Mr. Park has a
IP T
BEng in Mechanical Engineering awarded in 2013 and his MEng, awarded from the Changwon National University in 2015. He has interested in optical techniques for
measurement at the microscale and dimensional analysis in heat transfer and fluid mechanics.
SC R
At present, the primary application of his work is in the development of bio-microfluidic systems.
Microchannel 300 400 200
PCR device
29600 39700 640
PT
30000 40000 700
Variance (%)
Minimum
271.7 474.4 165.2
252.6 434.5 135.8
13.3 11.1 25
648.4
637.2
0.8 1.3 8.6
A
CC E
Width Length Thickness
260 450 150
ED
Depth Width Wall
Maximum
M
Average
N
Measured (μm)
A
Nominal (μm)
U
Table 1 Comparison of the nominal and measured dimensions of the 3D-printed PCR device
13