Smartphones as mobile microbiological laboratories

Smartphones as mobile microbiological laboratories

Journal Pre-proof Smartphones as mobile microbiological laboratories David S.Y. Ong, Mario Poljak PII: S1198-743X(19)30527-0 DOI: https://doi.org/1...

294KB Sizes 0 Downloads 62 Views

Journal Pre-proof Smartphones as mobile microbiological laboratories David S.Y. Ong, Mario Poljak PII:

S1198-743X(19)30527-0

DOI:

https://doi.org/10.1016/j.cmi.2019.09.026

Reference:

CMI 1797

To appear in:

Clinical Microbiology and Infection

Received Date: 13 August 2019 Revised Date:

24 September 2019

Accepted Date: 29 September 2019

Please cite this article as: Ong DSY, Poljak M, Smartphones as mobile microbiological laboratories, Clinical Microbiology and Infection, https://doi.org/10.1016/j.cmi.2019.09.026. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Narrative Review Smartphones as mobile microbiological laboratories

David S. Y. Ong,1,2 Mario Poljak3

1. Department of Medical Microbiology and Infection Control, Franciscus Gasthuis & Vlietland, Rotterdam, The Netherlands; 2. Department of Epidemiology, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands; 3. Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia;

Corresponding author: David S. Y. Ong, MD, PharmD, PhD, Kleiweg 500, 3045 PM Rotterdam. E-mail: [email protected]

Word count (manuscript): 2,775

Keywords: Smartphone, Mobile, Diagnostics, Point-of-care testing, Infection, Medical technology

1

Abstract

Background: Point-of-care (POC) tests provide an alternative to traditional laboratory-based diagnostics due to reduced turnaround-times, portability and no need for highly trained laboratory staff. Smartphones can be integrated into POC platforms because of their multifunctionality, enabled by high-quality digital cameras, computer processors, touchscreen interface and wireless data transfer. It is predicted that by 2020 about 80% of the world population will use smartphones. Objectives: This review summarises the current state of the art regarding smartphones as part of a mobile microbiological laboratory. Sources: Selected peer-reviewed publications on smartphone-based microbiological testing published between January 2015 and August 2019. Content: Smartphones can be used as instrumental interfaces, dongles, microscopes, or test result readers (brightfield, colorimetric and fluorescent measurements), or combined with amplification methods such as loop-mediated isothermal amplification (LAMP) tests in portable POC test platforms. Smartphone-based tests offer opportunities for microbiological diagnostics in remote areas and both resource-limited and resource-rich settings. Wireless connectivity may facilitate epidemiological studies and creation of spatiotemporal disease prevalence maps. However, the current analytical performance of many smartphone-based POC tests must be improved and carefully validated in clinical settings by comparison with current diagnostic standards. Implications: Recent developments in smartphone-based POC tests for infectious diseases are promising, as evidenced by results from many proof-of-concept studies. Further progress will foster large-scale implementation of smartphone-based POC as mobile microbiological laboratories in the near future.

Word count (abstract): 224

2

Introduction

Rapid and accurate microbiological diagnostics is essential in our highly dynamic field, where there are continuous threats of (re-)emerging infections, increasing antimicrobial resistance and increasing risk for several infectious diseases due to aging, poverty, global travel and migration [1]. Currently, most routine microbiological tests are confined to specialised microbiological or centralised laboratories. Subsequently, transportation times of patient samples to laboratories contribute to longer turnaround times. Resource-rich settings can afford advanced technologies, which require costly instrumentation and well-trained laboratory staff [1]. In contrast, traditional laboratory-based tests are often unfeasible in resource-limited settings due to a lack of laboratory facilities and/or personnel. In these settings point-of-care (POC) tests may provide an alternative and viable solution. POC tests are potentially attractive because of reduced turnaround times, no need for highly-trained laboratory staff and specific advantages such as portability, simplicity and independence from full laboratory or hospital infrastructure. Nevertheless, only limited microbiological POC tests have been implemented in routine clinical practice in both resource-limited and resource-rich countries for several reasons, including suboptimal sensitivity or specificity of POC tests compared to traditional laboratory tests, higher cost per test and unsuitability for multiple simultaneous testing [2,3]. Smartphones have been increasingly mentioned as promising POC platforms [2]. Smartphones are mobile phones that perform many of the functions of a computer and usually have touchscreen interfaces, internet access and operating systems. The first smartphones date from the early 2000s. Smartphones have rapidly become more advanced and include standard features like digital cameras, computer processors and wireless data transfer. Smartphones are also increasingly performing tasks previously performed only by laptops or desktop computers. Furthermore, smartphones are being mass produced, and it is predicted that by 2020 about 80% of the world population will use smartphones [4]. This makes smartphones ideal candidates for field-portable

3

biomedical measurement tools including microbiological POC tests that could significantly contribute to easier access to diagnostic testing, especially in resource-limited countries. This review summarises the current state of the art regarding smartphones as part of a mobile microbiological laboratory.

Smartphones as instrumental interfaces or accessory diagnostic tools

Smartphones can be used as interfaces for human operators to initiate and control the analytical process. An example is a diagnostic platform in which a microfluidic cassette together with a smartphone replaced all functions of a laboratory-based immunoassay for detecting anti-HIV antibodies and treponemal-specific and nontreponemal antibodies for syphilis [5]. The smartphone provided the software and power. In a blinded experiment, healthcare workers obtained whole blood via fingerprick from 96 patients. Results were obtained in 15 minutes and showed a sensitivity of 92 to 100% and specificity of 79 to 100% compared to laboratory-based HIV serology and rapid plasma reagin. Patients preferred the smartphone-based test over the laboratory-based test because of the low turnaround time and the need for only a single fingerprick. Another example is the use of smartphones as accessory diagnostic tools. Speakers and microphones in current smartphones were used for assessing eardrum mobility to determine the presence of middle ear fluid for diagnosing acute otitis media and otitis media with effusion [6]. The smartphone’s speaker sent a soft acoustic chirp into the ear canal, its microphone detected reflected sound from the eardrum and it used a logistic regression machine learning model to classify these reflections. An AUC of 0.90, sensitivity of 85% and specificity of 82% were achieved. In addition to the smartphone, this low-cost approach requires only a paper funnel and minimal expertise.

4

Smartphones as microscopes or test result readers

Readout instruments are essential components of many microbiological tests [7]. Most readout instruments are large and expensive. Smartphones have cameras that can be used as microscopes or digital readout tools using brightfield, colorimetric and fluorescent measurements to analyse samples.

Brightfield method Brightfield technology is based on illuminating samples with white light that is transmitted through the samples and attenuated in dense areas, causing observed contrasts [7]. This technique allows the observation of living cells or large biomolecules, which makes it especially suitable for the detection of parasites. In a pilot study with 33 potentially Loa loa–infected patients, a smartphone microscope was able to detect this parasite in whole blood collected by fingerprick [8]. Video microscopy using the smartphone camera was combined with automated sample scanning and quantitative detection by an image-processing algorithm. This algorithm automatically identified disturbances in the blood caused by moving microfilariae by subtracting subsequent frames of the video to generate a difference image, where regions of high intensity corresponded to the motion of microfilariae. In comparison to manual thick smear counts, specificity and sensitivity were 94% and 100%, respectively. Processing time was only 2 minutes and a glass capillary and a lancet were the only additional requirements. In a subsequent study, this diagnostic POC tool was used in 16,259 participants screened for implementation of an ivermectin-based community treatment strategy for eliminating onchocerciasis and lymphatic filariasis [9]. Importantly, patients should not receive ivermectin when coinfected by Loa loa because of the risk of serious adverse events. This tool had a specificity of 99.7% (95% confidence interval [CI] 99.6–99.8) and a negative predictive value of 99.7% (95%CI 99.6–99.7) compared to thick blood smear microscopy.

5

In two studies smartphone-based microscopies were used to detect Schistosoma eggs. The first was applied for detecting Schistosoma haematobium infection in 60 urine samples from schoolchildren [10]. The microscope consisted of a 3D-printed custom-designed optomechanical unit attached to the smartphone back-camera. Compared to a conventional light microscope, the lowcost smartphone microscope had a sensitivity of 72% (95%CI 56–84), specificity of 100% (95%CI 76– 100), positive predictive value of 100% (95%CI 86–100) and negative predictive value of 57% (95%CI 37–75). In the second study, the smartphone-based brightfield microscope was able to detect Schistosoma eggs in urine or faeces of schoolchildren during an epidemiologic survey [11]. Although promising, future studies are necessary to improve sensitivity and specificity in comparison to the gold standard of microscopy by an experienced diagnostician. In contrast to previously mentioned studies in the field of parasitology, smartphone-based imaging can also be applied for mycological testing. The smartphone camera in combination with a pocket magnifier was used as a POC test to detect fungal hyphae [12]. After corneal scraping, the smear was Gram stained and potassium hydroxide wet mounted. In comparison to light microscopy by an experienced microbiologist, smartphone-based digital imaging yielded similar findings, but was significantly less expensive.

Colorimetric method Colorimetry assesses changes in absorbance or reflectance of an analyte-reagent complex [7]. Two studies applied this particular method in serological testing. In the first study, a POC test based on a lateral flow immunoassay was developed for rapid detection of anti-Ebola IgG antibodies [13]. Patients’ serum was dropped onto the reagent strip; when anti-Ebola antibodies are present, a reddish-purple line appears on the strip. A custom-built app calculated the relative strength of the test line and determined the result. The test had 100% sensitivity and 98% specificity compared to standard whole antigen enzyme-linked immunosorbent assay (ELISA) when validated on 90 Ebola survivors and 31 non-infected controls. Advantages of this test are a turnaround time of 15 minutes,

6

low cost and possible implementation outside centralised laboratories, which is extremely important for patient management during outbreaks. In contrast to lateral flow immunoassays, ELISAs are usually more sensitive and faster, and they can generate quantitative results and be used multiple times. A smartphone-based ELISA platform coupled with a 3D-printed opto-mechanical attachment holding a light-emitting-diode (LED) array that illuminates a 96-well microtiter plate showed accuracies of 99.6%, 98.6%, 99.4% and 99.4% for mumps, measles, HSV-1 and HSV-2 antibodies, respectively [14].

Fluorescence measurements Fluorescence is the emission of light produced by a substance that has absorbed light or other electromagnetic radiation [7], and many smartphone-based prototypes use fluorescence to detect antibodies or nucleic acids. Three studies applied this method for virology diagnostics. For rapid detection of Ebola and Marburg filoviruses, a multiplexed platform was developed using a 3D-printed hardware attachment with the assay chip in panel that captured specific antibodies with microarrayed recombinant antigens of six species of filoviruses, and a smartphone fluorescent reader for test result interpretation [15]. The smartphone provided a user-friendly interface to manage testing, acquire test results and communicate with cloud service. In samples of non-human primates that received a live attenuated Ebola virus vaccine, the smartphone reader system clearly distinguished between sera containing anti-Ebola antibodies and non-vaccinated controls. The processing time was 20 minutes. Another study showed that a smartphone-based fluorescent lateral flow immunoassay platform was able to rapidly detect Zika virus NS1 antigen in complex biological samples with high sensitivity and specificity [16]. A 3D-printed plastic attachment integrated a smartphone, a highpower ultraviolet LED, optical filters, an external lens and a power unit. The fluorescence signal captured by the smartphone camera is processed to calculate fluorescence intensity. Also important are the rapid diagnostics of emerging respiratory infections. Avian influenza threatens to spread to

7

humans as a zoonotic infection [17]. A portable smartphone-based fluorescent diagnostic system was designed to simultaneously detect influenza A and its H5 subtype on a single strip and provided quantitative analysis with high accuracy. The system was evaluated in throat swab samples of 14 H5N1-confirmed patients and a heterogeneous group of 41 controls with non-influenza respiratory viruses. Sensitivity was 93% and 79% and specificity was 100% and 97% for influenza A and H5 subtype detection, respectively. In contrast to the aim of identification of the causative agent(s) in studies described above, the following study concerns antimicrobial susceptibility. An automated and cost-effective smartphone-based 96-well microtiter-plate reader was capable of performing antimicrobial susceptibility testing (AST) without trained diagnosticians [18]. The system included a smartphone and a 3D-printed attachment. The smartphone-reader met U. S. Food and Drug Administration (FDA)–defined AST criteria, with a detection accuracy of 98%, minimum inhibitory concentration accuracy of 95% and drug-susceptibility interpretation accuracy of 99%. However, important limitations are: (i) the need to prepare the microtiter plate with filling-specific drug concentrations and the isolates that need to be tested in each well, (ii) the possibility to test only single isolate at a time, and (iii) the need to know the identity of the bacterial isolate to provide a correct susceptibility interpretation. Overall, important advantages of fluorescence measurements are high sensitivity, simple operation and strong specificity. However, common limitations of fluorescence imaging include auto-fluorescence of the paper substrate, heterogeneity in spectral sensitivities of smartphone camera channels and correlation of measured fluorescence intensity with both the number of fluorophores as well as excitation intensity. Radiometric mobile phone imaging of long Stokes-shift quantum dots is an example of improving sensitivity and tackling these limitations [19].

8

Smartphones in combination with loop-mediated isothermal amplification tests

The advantage of loop-mediated isothermal amplification (LAMP) over other amplification methods is the need for only simple and low-cost equipment because of the isothermal nature of the assays, which makes it attractive to be used in POC settings. A field-portable, cost-effective and lightweight smartphone-based POC platform using LAMP achieved a 69-fold increase in signal above background [20], showing the promising potential of combining LAMP with smartphone-based platforms. Recently, a smartphone-based real-time LAMP system was developed for pathogen identification in urinary sepsis patients [21]. The custom-built smartphone application determined the genome copy-number of bacterial pathogens in real time. The performance of this system matched that of standard bacterial analysis of urine and required only 1 hour of turnaround time in comparison to 18 to 28 hours in traditional diagnostics. Furthermore, among patients with bacteremic complications of their urinary sepsis, pathogen identification from the urine matched that from the blood. Importantly, the system did not exhibit false positives in patients with clinically negative urine cultures, and it is configurable for simultaneous detection of multiple pathogens. Altogether, this platform offered rapid diagnosis at a low cost. However, a significant limitation is that some of the data needed to be calculated using software only available on a personal computer and the inability to perform susceptibility testing. Several smartphone-based diagnostic tests for flaviviruses and alphaviruses were developed. One platform was able to rapidly detect Zika, chikungunya and dengue viruses in human blood, urine and saliva by coupling reverse-transcription LAMP with the quenching of unincorporated amplification signal reporters technique [22]. This platform offered simultaneous detection of multiple viruses in a single reaction and employed an algorithm utilising chromaticity to analyse fluorescence signals. Furthermore, the application controlled the low-powered isothermal heating module and a multicolour LED excitation module via Bluetooth and acquired images from the smartphone camera. Another POC test to detect Zika, dengue and chikungunya viruses from whole

9

blood samples was based on a microfluidic platform, which performed minimal sample processing followed by real-time reverse-transcription LAMP on the same card with pre-dried primers specific to viral targets [23]. A smartphone was used to acquire real-time images of the amplification reaction and display a visual readout of the assay, including quantification of the pathogen load. A limit of detection of 1.56e5 PFU/ml of Zika from whole blood was achieved. A similar application of LAMP was applied for quantitative detection of Zika in urine and saliva and HIV in blood [24]. The platform combined a bioluminescent assay in real time with LAMP and was tested using spiked patient samples. Another important innovation is the development of a rapid molecular POC test for malaria. Among 220 children, a smartphone diagnostic platform was tested to detect malaria DNA in blood samples [25]. This platform used paper folding to integrate the different sample preparation steps required for LAMP onto a paper microfluidic device. Channels formed by hot wax printing either repel or attract blood moving through the structure by capillary force prior to detecting malaria DNA. Compared to laboratory-based real-time PCR, the sensitivity of this test was 98%, which is significantly higher than microscopy (85%) and rapid immunoassay tests (82%). Advantages are low costs, needing only fingerprick blood and higher specificity in comparison to lateral flow immunoassays resulting in fewer false-positive results. The costs of the platform are largely determined by the freeze-dried enzymes and reagents used to trigger LAMP. Finally, an interesting development is the combined use of LAMP and micromotor motion for molecular detection of HIV-1 RNA by smartphone-based optical sensing [26]. This technique is based on the presence of RNA forming large-sized amplicons that reduce the motion of catalytic micromotors powered by metal nanoparticles. The platform tested achieved qualitative detection at a threshold value of 1,000 HIV-1 particles per ml with 99% specificity and 95% sensitivity. This may contribute to the possibility for early diagnosis, because most other POC tests detect anti-HIV antibodies by lateral flow immunoassays and could potentially miss the early phase of an acute HIV infection.

10

Future prospects

Based on promising proof-of-concept studies summarised in this review and the worldwide availability of smartphones, it is likely that smartphone-based POC tests will soon be increasingly used for diagnostic purposes. Smartphone-based tests may provide opportunities for diagnostics in both remote areas and resource-limited settings. Moreover, wireless connectivity may facilitate epidemiological studies and the creation of spatiotemporal maps of disease prevalence. However, several challenges remain before the routine use of smartphone-based POC tests. First, the analytical performance (i.e., especially accuracy and sensitivity) of many smartphone-based tests must be improved. Second, most tests detect only single or a few targets. However, in clinical practice there is often a need to test for multiple pathogens simultaneously because the clinical presentation is usually not entirely specific for a single infectious disease. Third, in accordance with good diagnostic practice, all tests should be carefully validated in clinical settings and compared to current diagnostic standards before implementation. Subsequently, the infrastructure should allow periodic maintenance and regular checks of smartphone devices similar to traditional laboratory tests to ensure quality and safety in a clinical setting. Fourth, cost of reagents and consumables should probably be further reduced before large-scale implementation in resource-limited settings. The use of 3D-print technology on site has reduced some costs by omitting transportation costs. Fifth, data transfer to a server or a cloud should be rapid and safe, and only considered when personal data privacy is guaranteed. In conclusion, recent developments in smartphone-based POC tests are promising. Although important challenges remain, it is likely that further progress will foster the widespread use of smartphone-based POC tests Importantly, similar to other microbiological tests the added value of a smartphone-based POC test relies on both its performance characteristics as well as adequate

11

interpretation of the test result that considers the clinical context and all potential pitfalls of the particular test. Inevitably, clinical microbiologists as experts in bridging laboratory and clinical practice, should be endorsed to take a leading role in the consideration, implementation, quality control and use of smartphone-based POC tests as mobile microbiological laboratories as well as interpretation of the test results.

Conflict of interest The authors declare no conflicts of interest.

Funding No external funding was received for this work.

Acknowledgements A part of this work was presented at the 29th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) 2019 during the “@mobilemicrobiologylaboratory” symposium in Amsterdam, The Netherlands.

12

References [1]

[2] [3] [4] [5]

[6] [7]

[8]

[9]

[10]

[11]

[12]

[13]

[14]

[15]

[16]

[17]

Halliday JEB, Hampson K, Hanley N, Lembo T, Sharp JP, Haydon DT, et al. Driving improvements in emerging disease surveillance through locally relevant capacity strengthening. Science 2017;357:146–8. doi:10.1126/science.aam8332. Zarei M. Infectious pathogens meet point-of-care diagnostics. Biosens Bioelectron 2018;106:193–203. doi:10.1016/j.bios.2018.02.007. Chen H, Liu K, Li Z, Wang P. Point of care testing for infectious diseases. Clin Chim Acta 2019;493:138–47. doi:10.1016/j.cca.2019.03.008. Koydemir HC, Ozcan A. Mobile phones create new opportunities for microbiology research and clinical applications. Future Microbiol 2017;12:641–4. doi:10.2217/fmb-2017-0046. Laksanasopin T, Guo TW, Nayak S, Sridhara AA, Xie S, Olowookere OO, et al. A smartphone dongle for diagnosis of infectious diseases at the point of care. Sci Transl Med 2015;7:273re1–273re1. doi:10.1126/scitranslmed.aaa0056. Chan J, Raju S, Nandakumar R, Bly R, Gollakota S. Detecting middle ear fluid using smartphones. Sci Transl Med 2019;11:eaav1102. doi:10.1126/scitranslmed.aav1102. Liu J, Geng Z, Fan Z, Liu J, Chen H. Point-of-care testing based on smartphone: the current state-of-the-art (2017-2018). Biosens Bioelectron 2019;132:17–37. doi:10.1016/j.bios.2019.01.068. D’Ambrosio MV, Bakalar M, Bennuru S, Reber C, Skandarajah A, Nilsson L, et al. Point-ofcare quantification of blood-borne filarial parasites with a mobile phone microscope. Sci Transl Med 2015;7:286re4–286re4. doi:10.1126/scitranslmed.aaa3480. Kamgno J, Pion SD, Chesnais CB, Bakalar MH, D’Ambrosio MV, Mackenzie CD, et al. A testand-not-treat strategy for onchocerciasis in Loa loa–endemic areas. N Engl J Med 2017;377:2044–52. doi:10.1056/NEJMoa1705026. Bogoch II, Koydemir HC, Tseng D, Ephraim RKD, Duah E, Tee J, et al. Evaluation of a mobile phone–based microscope for screening of Schistosoma haematobium infection in rural Ghana. Am J Trop Med Hyg 2017;96:1468–71. doi:10.4269/ajtmh.16-0912. Koydemir HC, Coulibaly JT, Tseng D, Bogoch II, Ozcan A. Design and validation of a widefield mobile phone microscope for the diagnosis of schistosomiasis. Travel Med Infect Dis 2018. doi:10.1016/j.tmaid.2018.12.001. Agarwal T, Bandivadekar P, Satpathy G, Sharma N, Titiyal JS. Detection of fungal hyphae using smartphone and pocket magnifier: going cellular. Cornea 2015;34:355–7. doi:10.1097/ICO.0000000000000359. Brangel P, Sobarzo A, Parolo C, Miller BS, Howes PD, Gelkop S, et al. A serological point-ofcare test for the detection of IgG antibodies against Ebola virus in human survivors. ACS Nano 2018;12:63–73. doi:10.1021/acsnano.7b07021. Berg B, Cortazar B, Tseng D, Ozkan H, Feng S, Wei Q, et al. Cellphone-based hand-held microplate reader for point-of-care testing of enzyme-linked immunosorbent assays. ACS Nano 2015;9:7857–66. doi:10.1021/acsnano.5b03203. Natesan M, Wu S-W, Chen C-I, Jensen SMR, Karlovac N, Dyas BK, et al. A smartphone-based rapid telemonitoring system for Ebola and Marburg disease surveillance. ACS Sens 2019;4:61–8. doi:10.1021/acssensors.8b00842. Rong Z, Wang Q, Sun N, Jia X, Wang K, Xiao R, et al. Smartphone-based fluorescent lateral flow immunoassay platform for highly sensitive point-of-care detection of Zika virus nonstructural protein 1. Anal Chim Acta 2019;1055:140–7. doi:10.1016/j.aca.2018.12.043. Yeo S-J, Kang H, Dao TD, Cuc BT, Nguyen ATV, Tien TTT, et al. Development of a smartphone-based rapid dual fluorescent diagnostic system for the simultaneous detection of influenza A and H5 subtype in avian influenza A-infected patients. Theranostics 2018;8:6132–48. doi:10.7150/thno.28027.

13

[18]

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26]

Feng S, Tseng D, Di Carlo D, Garner OB, Ozcan A. High-throughput and automated diagnosis of antimicrobial resistance using a cost-effective cellphone-based micro-plate reader. Sci Rep 2016;6:39203. doi:10.1038/srep39203. Shah KG, Singh V, Kauffman PC, Abe K, Yager P. Mobile phone ratiometric imaging enables highly sensitive fluorescence lateral flow immunoassays without external optical filters. Anal Chem 2018;90:6967–74. doi:10.1021/acs.analchem.8b01241. Kong JE, Wei Q, Tseng D, Zhang J, Pan E, Lewinski M, et al. Highly stable and sensitive nucleic acid amplification and cell-phone-based readout. ACS Nano 2017;11:2934–43. doi:10.1021/acsnano.6b08274. Barnes L, Heithoff DM, Mahan SP, Fox GN, Zambrano A, Choe J, et al. Smartphone-based pathogen diagnosis in urinary sepsis patients. EBioMedicine 2018;36:73–82. doi:10.1016/j.ebiom.2018.09.001. Priye A, Bird SW, Light YK, Ball CS, Negrete OA, Meagher RJ. A smartphone-based diagnostic platform for rapid detection of Zika, chikungunya, and dengue viruses. Sci Rep 2017;7:44778. doi:10.1038/srep44778. Ganguli A, Ornob A, Yu H, Damhorst GL, Chen W, Sun F, et al. Hands-free smartphone-based diagnostics for simultaneous detection of Zika, chikungunya, and dengue at point-of-care. Biomed Microdevices 2017;19:73. doi:10.1007/s10544-017-0209-9. Song J, Pandian V, Mauk MG, Bau HH, Cherry S, Tisi LC, et al. Smartphone-based mobile detection platform for molecular diagnostics and spatiotemporal disease mapping. Anal Chem 2018;90:4823–31. doi:10.1021/acs.analchem.8b00283. Reboud J, Xu G, Garrett A, Adriko M, Yang Z, Tukahebwa EM, et al. Paper-based microfluidics for DNA diagnostics of malaria in low resource underserved rural communities. Proc Natl Acad Sci USA 2019;116:4834–42. doi:10.1073/pnas.1812296116. Draz MS, Kochehbyoki KM, Vasan A, Battalapalli D, Sreeram A, Kanakasabapathy MK, et al. DNA engineered micromotors powered by metal nanoparticles for motion based cellphone diagnostics. Nat Commun 2018;9:4282. doi:10.1038/s41467-018-06727-8.

14