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High-quality flexible antenna fabricated by ion-exchange technique
Materials Letters 256 (2019) 126643
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
High-quality flexible antenna fabricated by ion-exchange technique Jinhua Peng a, Ke Wang a, Linhui Wu a, Zhangming Liu a, Chang Qi b, Xinzhi Shi b,⇑, Shuangli Ye a,⇑ a b
School of Printing and Packaging, Wuhan University, Wuhan 430072, Hubei Province, People’s Republic of China Electronic Information School, Wuhan University, Wuhan 430072, Hubei Province, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 22 July 2019 Received in revised form 23 August 2019 Accepted 7 September 2019 Available online 9 September 2019 Keywords: Flexible antenna Ion exchange technique Surfaces Electronic materials Nanoparticles
a b s t r a c t In this work, low-cost ion exchange technique coupled with printed-mask method has successfully been applied on the fabrication of high-quality flexible antennas. Nano-silver particles are chosen as conductive material of the CPW-fed antenna. The structure of the antennas is well-defined by the inkjet printing method. The experimental results indicate that a compact, smooth and highly-defined silver pattern is formed on the PI film with thickness of 800 nm, particle size of 50 nm and sheet resistance of 2.34 X/sq. A peak gain of 42.68 dB at resonant frequency 2.4 GHz nicely accords with the simulated result by ANSYS Electronics, demonstrating that the desired impedance matching can be realized. Moreover, the PI-based antenna shows excellent flexibility with a low sensibility to the bending tests. Therefore, the flexible patterned antenna by ion exchange technique and printed mask is suitable for flexible wireless electronics devices such as wearable devices, RFID labels and wireless mobile communication. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Flexible electronics as an emerging electronic technique have been increasingly gained attention and concerns in a way that may subvert traditional electronic devices using the rigid Printed Circuit Boards (PCBs) [1–5]. With the development of flexible electronics, the antenna also has a tendency to be gradually light weight and flexibility [6]. The integration of flexible antenna with other electronic devices can be the trend of wireless electronic devices in the future. Consequently, the antenna has been designed on the paper and polymer substrates. The former is a flexible, translucent and porous, which is easy to be wrinkle [7]. By contrary, polymer substrates have the characteristics of hardness, elasticity and flexibility and can be used in rough circumstance [8]. The fabrication methods of antennas have been mainly based on etching and electroplating process. These techniques are characterized by complex process, high cost and not friendly to the environment with heavy pollution [9]. Therefore, application of printing technique is being highlighted by researchers [10,11]. This method has the advantages of efficiency and lower cost than that of traditional techniques, while it also has prominent weakness, such as uneven ink leakage, low conductivity, poor cohesion and adhesion to a substrate. Also, a sintering process above 300 °C has to be applied to improve the performance of antenna and metal–polymer adhesion [12]. ⇑ Corresponding authors. E-mail addresses: [email protected] (X. Shi), [email protected] (S. Ye). https://doi.org/10.1016/j.matlet.2019.126643 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
In this paper, in-situ ion exchange technique coupled with printed-mask method has been successfully applied on the fabrication of high-quality flexible silver antenna. The results indicate that a compact and highly-defined silver pattern is formed on the polyimide (PI) film with good electrical conductivity and proper adhesion. Moreover, the PI-based antenna shows excellent flexibility. This technique can also be extended to fabricate other metal/metal oxide patterns coating on polymeric substrates for high-quality flexible electronic devices. 2. Experiment 2.1. Antenna preparation Potassium hydroxide (KOH), hydrazine monohydrate (N2H4H2O), acetone and ethanol are all purchased from Sinopharm Chemical Reagent Co., Ltd. Silver nitrate (AgNO3) is provided by Shanghai Lingfeng Chemical Reagent Co., Ltd. PI films are obtained from Zhongshan Jinlvye Electronic Materials Co., Ltd. Deionized water is made by Ultrapure Water Machine (ZYUPK-I-20T, Chengdu, China). All chemical materials are of analytical quality and used without further purification. The preparation procedure for the CPW-fed antenna mainly includes four steps: hydrolyzing, ion exchange, masking and silver ion reduction, as shown in Fig. 1. Firstly, the cleaned PI film is immersed into 4 M KOH solution to make K+ ions embedded in the PI surface. Secondly, as-prepared films are immersed into Ag (NH3)2OH for several minutes. By ion exchange, the K+ ions are
2
J. Peng et al. / Materials Letters 256 (2019) 126643
Fig. 1. The schematic diagram of the Ag/PI antenna fabrication.
replaced by Ag+ ions. Subsequently, the surface-modified PI films are printed for masking to form antenna pattern by the inkjet printer (LJ2205, Lenovo). After that, the patterned films were directly dipped into N2H4H2O to reduce silver ions to silver nanoparticles. Finally, the fabricated antennas were dried before test. The geometry of the proposed antenna is also shown in Fig. 1. Dimensions of the proposed antenna are as follows (all in millimeters): L = 68, W = 43.3, R1 = 13, R2 = 4, L1 = 30, W1 = 18.8, L2 = 41.98, W2 = 3.5. Moreover, Compared with the microstrip antenna, the CPW-fed
antenna has advantages in low dispersion and simple manufacture without hole or coaxial line. 2.2. Characterization of the CPW-fed antenna The structure and crystalline phase of the Ag/PI antenna are identified by X-ray diffraction (XRD, x’pert3 powder, Cu-ka, PANalytical B.V). The morphology of the films is characterized by Field Emission Scanning Electron Microscope (FESEM, Zeiss SIGMA, Carl
Fig. 2. X-ray diffraction pattern for the Ag/PI antenna (a), SEM micrographs for the surface (b) and (c), the cross-section (d) of the Ag/PI antenna.
J. Peng et al. / Materials Letters 256 (2019) 126643
Zeiss AG). The resistance is measured by Digital Multimeter (DMM, 34401A, Agilent Technologies Inc). The return loss (S11) and radiation patterns of the antenna are analyzed by Vector network analyzer (VNA, E5062A, Agilent/Keysight).
3. Results and discussion The XRD pattern of the Ag/PI antenna is presented in Fig. 2(a). The diffraction peaks at 38.15°, 44.35°, 64.60° and 77.50° can be assigned to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, respectively. These peaks are highly coincident with JCPDS 4-783, indicating that the prepared silver is composed of the face-centered cubic nanoparticles. This phenomenon illustrates that high quality silver nanoparticles are formed, which is in favor of good conductivity. More importantly, there is no other diffraction peaks can be observed from XRD measurement. Fig. 2(b) and (c) shows the morphology of Ag/PI antenna by SEM characterization. It can be seen that the continuous silver nanolayer is uniformly and densely distributed on the PI films. The high magnification images shows that almost all particles are spherical shape with size around 50 nm. It can be found that the silver layer is only about 800 nm by the cross-section SEM image, as shown in Fig. 2(d). Therefore, compared with inkjet printing and screen printing [13], ion exchange technique does not need a sintering process, and can obtain much thinner conductive materials for membrane antenna with the advantages of metal consumption saving. The experimental and simulated results of reflection coefficient S11 of the fabricated antenna is shown in Fig. 3(a). It can be found that the measured resonant frequency accords with the simulation
3
result by ANSYS Electronics at 2.4 GHz with no frequency shift. Moreover, a peak gain of 42.68 dB at 2.4 GHz is obtained as well, which has a good agreement with the simulated results. The simulated and measured E-plane and H-plane radiation patterns of the proposed antenna at 2.4 GHz are shown in Fig. 3(b) and (c). It can be found that the radiation patterns are ‘‘800 shape, the simulated and measured patterns are highly coincident. These results demonstrate that antenna prepared by the ion exchange technique shows better performance than antenna fabricated by inkjet and screening printing techniques [14]. In conclusion, the ion exchange technique is an effective method to fabricate the high quality flexible antenna, which can achieve good impedance matching. The stability of the flexible antenna is extraordinarily critical and necessary. Zhang et al. [15] has shown that Ag/PI films has good thermal stability. On the other hand, the bendability tests have been carried out to verify the stability of Ag/PI antenna under bending state inn our work. For this purpose, the antenna is attached on the cylinder with Bending angle h = 0°, 66°, 76° and 90°. The Fig. 3(d) shows the changes of return loss under bending angle. It can be found that the difference of return loss for antennas with and without bending is slight, indicating that the performance of the antenna keeps stable under bending state. Resonant frequency is 2.40 GHz in the flat state. And it is 2.39, 2.34 and 2.27 GHz in the bending state with 66°, 76°and 90° bending angle, respectively. Four bandwidth are 2.26–2.64, 2.22–2.34, 2.25–2.45 and 2.27–2.52 GHz, respectively. Moreover, as it can be seen from the Fig. 3(d), the reflection coefficient S11 is maintained below 30 dB for these cases, demonstrating a good impedance matching. The illustration in the Fig. 3(d) shows the fabricated antenna with the bending state. Therefore, the fabricated antenna exhibits
Fig. 3. The simulated (black dotted line) and measured (red solid line) S11 (a), radiation patterns in the E-plane (b) and H-plane (c) of the antenna without bending at 2.4 GHz; The measured S11 with different bending angle (d).
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J. Peng et al. / Materials Letters 256 (2019) 126643
good stability in impedance matching and resonant frequency with regard to bending effects.
4. Conclusion The high-quality silver-based antenna at 2.4 GHz has been successfully manufactured though the ion exchange technique on the PI membrane. The silver nanoparticles which enable the film to be metallized are uniformly grown and dispersed on the PI surface. The thickness of silver layer is only 800 nm with sheet resistance of 2.34 X/sq, which shows advantage of low silver consumption. The resonant frequency of measured and simulated results are all at 2.4 GHz by ANSYS Electronics, which is highly consistent with each other. Moreover, the flexible antenna exhibits much low susceptibility to bending tests and keep the good stability. In conclusion, ion exchange technique and printed-mask method are suitable to fabricate the antenna on the polymer materials with the merit of flexibility, robustness, simple process as well as remarkable stability for wireless flexible electronics applications.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment The authors gratefully acknowledge the financial support offered by the National Natural Science Foundation of China (Grant Nos. 51371129 and 11174226). References [1] S. Gong, W. Cheng, Adv. Electron. Mater. 3 (2017) 1600314. [2] M.T. Islam, T. Alam, I. Yahya, M. Cho, Sensors (Switzerland) 18 (2018) 4212. [3] K. Ruan, Q. Hu, Y. Wang, B. Long, L. Chen, Y. Wu, Mater. Lett. 236 (2019) 383– 386. [4] Y. Gao, C. Lu, Y. Guohui, J. Sha, J. Tan, F. Xuan, Nanotechnology. 30 (2019) 325502. [5] X. Li, R.U.R. Sagar, L. Zhong, Y. Liu, D. Hui, M. Zhang, Mater. Lett. 248 (2019) 43– 47. [6] F. Xu, D. Zhang, Y. Liao, F. Xie, H. Zhang, Ceram. Int. 45 (2019) 8914–8918. [7] D. Tobjörk, R. Österbacka, Adv. Mater. 23 (2011) 1935–1961. [8] M.O. Sallam, S.M. Kandil, V. Volski, G.A.E. Vandenbosch, E.A. Soliman, IEEE Trans. Antennas Propag. 65 (2017) 4274–4277. [9] M. Yu, X. Zeng, Q. Song, L. Liu, J. Li, J. Clean. Prod. 113 (2016) 973–980. [10] S. Ahmed, F.A. Tahir, A. Shamim, H.M. Cheema, IEEE Antennas Wirel. Propag. Lett. 14 (2015) 1802–1805. [11] H.R. Khaleel, H.M. Al-Rizzo, D.G. Rucker, S. Mohan, IEEE Antennas Wirel. Propag. Lett. 11 (2012) 564–567. [12] S. Wünscher, R. Abbel, J. Perelaer, U.S. Schubert, J. Mater. Chem. C. 2 (2014) 10232–10261. [13] K. Janeczek, G. Kozioł, T. Serzysko, M. Jakubowska, in: Electron. Syst. Integr. Technol. Conf. ESTC 2010 - Proc., 2010, pp. 3–7. [14] J.J. Adams, J.S. Jur, H. Soewardiman, C.A. Muchler, H. Shahariar, Smart Mater. Struct. 27 (2018) 045008. [15] D.Y. Zhang, J. Liu, Y.S. Shi, Y. Wang, H.F. Liu, Q.L. Hu, L. Su, J. Zhu, J. Membr. Sci. 516 (2016) 83–93.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
High-quality flexible antenna fabricated by ion-exchange technique Jinhua Peng a, Ke Wang a, Linhui Wu a, Zhangming Liu a, Chang Qi b, Xinzhi Shi b,⇑, Shuangli Ye a,⇑ a b
School of Printing and Packaging, Wuhan University, Wuhan 430072, Hubei Province, People’s Republic of China Electronic Information School, Wuhan University, Wuhan 430072, Hubei Province, People’s Republic of China
a r t i c l e
i n f o
Article history: Received 22 July 2019 Received in revised form 23 August 2019 Accepted 7 September 2019 Available online 9 September 2019 Keywords: Flexible antenna Ion exchange technique Surfaces Electronic materials Nanoparticles
a b s t r a c t In this work, low-cost ion exchange technique coupled with printed-mask method has successfully been applied on the fabrication of high-quality flexible antennas. Nano-silver particles are chosen as conductive material of the CPW-fed antenna. The structure of the antennas is well-defined by the inkjet printing method. The experimental results indicate that a compact, smooth and highly-defined silver pattern is formed on the PI film with thickness of 800 nm, particle size of 50 nm and sheet resistance of 2.34 X/sq. A peak gain of 42.68 dB at resonant frequency 2.4 GHz nicely accords with the simulated result by ANSYS Electronics, demonstrating that the desired impedance matching can be realized. Moreover, the PI-based antenna shows excellent flexibility with a low sensibility to the bending tests. Therefore, the flexible patterned antenna by ion exchange technique and printed mask is suitable for flexible wireless electronics devices such as wearable devices, RFID labels and wireless mobile communication. Ó 2019 Elsevier B.V. All rights reserved.
1. Introduction Flexible electronics as an emerging electronic technique have been increasingly gained attention and concerns in a way that may subvert traditional electronic devices using the rigid Printed Circuit Boards (PCBs) [1–5]. With the development of flexible electronics, the antenna also has a tendency to be gradually light weight and flexibility [6]. The integration of flexible antenna with other electronic devices can be the trend of wireless electronic devices in the future. Consequently, the antenna has been designed on the paper and polymer substrates. The former is a flexible, translucent and porous, which is easy to be wrinkle [7]. By contrary, polymer substrates have the characteristics of hardness, elasticity and flexibility and can be used in rough circumstance [8]. The fabrication methods of antennas have been mainly based on etching and electroplating process. These techniques are characterized by complex process, high cost and not friendly to the environment with heavy pollution [9]. Therefore, application of printing technique is being highlighted by researchers [10,11]. This method has the advantages of efficiency and lower cost than that of traditional techniques, while it also has prominent weakness, such as uneven ink leakage, low conductivity, poor cohesion and adhesion to a substrate. Also, a sintering process above 300 °C has to be applied to improve the performance of antenna and metal–polymer adhesion [12]. ⇑ Corresponding authors. E-mail addresses: [email protected] (X. Shi), [email protected] (S. Ye). https://doi.org/10.1016/j.matlet.2019.126643 0167-577X/Ó 2019 Elsevier B.V. All rights reserved.
In this paper, in-situ ion exchange technique coupled with printed-mask method has been successfully applied on the fabrication of high-quality flexible silver antenna. The results indicate that a compact and highly-defined silver pattern is formed on the polyimide (PI) film with good electrical conductivity and proper adhesion. Moreover, the PI-based antenna shows excellent flexibility. This technique can also be extended to fabricate other metal/metal oxide patterns coating on polymeric substrates for high-quality flexible electronic devices. 2. Experiment 2.1. Antenna preparation Potassium hydroxide (KOH), hydrazine monohydrate (N2H4H2O), acetone and ethanol are all purchased from Sinopharm Chemical Reagent Co., Ltd. Silver nitrate (AgNO3) is provided by Shanghai Lingfeng Chemical Reagent Co., Ltd. PI films are obtained from Zhongshan Jinlvye Electronic Materials Co., Ltd. Deionized water is made by Ultrapure Water Machine (ZYUPK-I-20T, Chengdu, China). All chemical materials are of analytical quality and used without further purification. The preparation procedure for the CPW-fed antenna mainly includes four steps: hydrolyzing, ion exchange, masking and silver ion reduction, as shown in Fig. 1. Firstly, the cleaned PI film is immersed into 4 M KOH solution to make K+ ions embedded in the PI surface. Secondly, as-prepared films are immersed into Ag (NH3)2OH for several minutes. By ion exchange, the K+ ions are
2
J. Peng et al. / Materials Letters 256 (2019) 126643
Fig. 1. The schematic diagram of the Ag/PI antenna fabrication.
replaced by Ag+ ions. Subsequently, the surface-modified PI films are printed for masking to form antenna pattern by the inkjet printer (LJ2205, Lenovo). After that, the patterned films were directly dipped into N2H4H2O to reduce silver ions to silver nanoparticles. Finally, the fabricated antennas were dried before test. The geometry of the proposed antenna is also shown in Fig. 1. Dimensions of the proposed antenna are as follows (all in millimeters): L = 68, W = 43.3, R1 = 13, R2 = 4, L1 = 30, W1 = 18.8, L2 = 41.98, W2 = 3.5. Moreover, Compared with the microstrip antenna, the CPW-fed
antenna has advantages in low dispersion and simple manufacture without hole or coaxial line. 2.2. Characterization of the CPW-fed antenna The structure and crystalline phase of the Ag/PI antenna are identified by X-ray diffraction (XRD, x’pert3 powder, Cu-ka, PANalytical B.V). The morphology of the films is characterized by Field Emission Scanning Electron Microscope (FESEM, Zeiss SIGMA, Carl
Fig. 2. X-ray diffraction pattern for the Ag/PI antenna (a), SEM micrographs for the surface (b) and (c), the cross-section (d) of the Ag/PI antenna.
J. Peng et al. / Materials Letters 256 (2019) 126643
Zeiss AG). The resistance is measured by Digital Multimeter (DMM, 34401A, Agilent Technologies Inc). The return loss (S11) and radiation patterns of the antenna are analyzed by Vector network analyzer (VNA, E5062A, Agilent/Keysight).
3. Results and discussion The XRD pattern of the Ag/PI antenna is presented in Fig. 2(a). The diffraction peaks at 38.15°, 44.35°, 64.60° and 77.50° can be assigned to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, respectively. These peaks are highly coincident with JCPDS 4-783, indicating that the prepared silver is composed of the face-centered cubic nanoparticles. This phenomenon illustrates that high quality silver nanoparticles are formed, which is in favor of good conductivity. More importantly, there is no other diffraction peaks can be observed from XRD measurement. Fig. 2(b) and (c) shows the morphology of Ag/PI antenna by SEM characterization. It can be seen that the continuous silver nanolayer is uniformly and densely distributed on the PI films. The high magnification images shows that almost all particles are spherical shape with size around 50 nm. It can be found that the silver layer is only about 800 nm by the cross-section SEM image, as shown in Fig. 2(d). Therefore, compared with inkjet printing and screen printing [13], ion exchange technique does not need a sintering process, and can obtain much thinner conductive materials for membrane antenna with the advantages of metal consumption saving. The experimental and simulated results of reflection coefficient S11 of the fabricated antenna is shown in Fig. 3(a). It can be found that the measured resonant frequency accords with the simulation
3
result by ANSYS Electronics at 2.4 GHz with no frequency shift. Moreover, a peak gain of 42.68 dB at 2.4 GHz is obtained as well, which has a good agreement with the simulated results. The simulated and measured E-plane and H-plane radiation patterns of the proposed antenna at 2.4 GHz are shown in Fig. 3(b) and (c). It can be found that the radiation patterns are ‘‘800 shape, the simulated and measured patterns are highly coincident. These results demonstrate that antenna prepared by the ion exchange technique shows better performance than antenna fabricated by inkjet and screening printing techniques [14]. In conclusion, the ion exchange technique is an effective method to fabricate the high quality flexible antenna, which can achieve good impedance matching. The stability of the flexible antenna is extraordinarily critical and necessary. Zhang et al. [15] has shown that Ag/PI films has good thermal stability. On the other hand, the bendability tests have been carried out to verify the stability of Ag/PI antenna under bending state inn our work. For this purpose, the antenna is attached on the cylinder with Bending angle h = 0°, 66°, 76° and 90°. The Fig. 3(d) shows the changes of return loss under bending angle. It can be found that the difference of return loss for antennas with and without bending is slight, indicating that the performance of the antenna keeps stable under bending state. Resonant frequency is 2.40 GHz in the flat state. And it is 2.39, 2.34 and 2.27 GHz in the bending state with 66°, 76°and 90° bending angle, respectively. Four bandwidth are 2.26–2.64, 2.22–2.34, 2.25–2.45 and 2.27–2.52 GHz, respectively. Moreover, as it can be seen from the Fig. 3(d), the reflection coefficient S11 is maintained below 30 dB for these cases, demonstrating a good impedance matching. The illustration in the Fig. 3(d) shows the fabricated antenna with the bending state. Therefore, the fabricated antenna exhibits
Fig. 3. The simulated (black dotted line) and measured (red solid line) S11 (a), radiation patterns in the E-plane (b) and H-plane (c) of the antenna without bending at 2.4 GHz; The measured S11 with different bending angle (d).
4
J. Peng et al. / Materials Letters 256 (2019) 126643
good stability in impedance matching and resonant frequency with regard to bending effects.
4. Conclusion The high-quality silver-based antenna at 2.4 GHz has been successfully manufactured though the ion exchange technique on the PI membrane. The silver nanoparticles which enable the film to be metallized are uniformly grown and dispersed on the PI surface. The thickness of silver layer is only 800 nm with sheet resistance of 2.34 X/sq, which shows advantage of low silver consumption. The resonant frequency of measured and simulated results are all at 2.4 GHz by ANSYS Electronics, which is highly consistent with each other. Moreover, the flexible antenna exhibits much low susceptibility to bending tests and keep the good stability. In conclusion, ion exchange technique and printed-mask method are suitable to fabricate the antenna on the polymer materials with the merit of flexibility, robustness, simple process as well as remarkable stability for wireless flexible electronics applications.
Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgment The authors gratefully acknowledge the financial support offered by the National Natural Science Foundation of China (Grant Nos. 51371129 and 11174226). References [1] S. Gong, W. Cheng, Adv. Electron. Mater. 3 (2017) 1600314. [2] M.T. Islam, T. Alam, I. Yahya, M. Cho, Sensors (Switzerland) 18 (2018) 4212. [3] K. Ruan, Q. Hu, Y. Wang, B. Long, L. Chen, Y. Wu, Mater. Lett. 236 (2019) 383– 386. [4] Y. Gao, C. Lu, Y. Guohui, J. Sha, J. Tan, F. Xuan, Nanotechnology. 30 (2019) 325502. [5] X. Li, R.U.R. Sagar, L. Zhong, Y. Liu, D. Hui, M. Zhang, Mater. Lett. 248 (2019) 43– 47. [6] F. Xu, D. Zhang, Y. Liao, F. Xie, H. Zhang, Ceram. Int. 45 (2019) 8914–8918. [7] D. Tobjörk, R. Österbacka, Adv. Mater. 23 (2011) 1935–1961. [8] M.O. Sallam, S.M. Kandil, V. Volski, G.A.E. Vandenbosch, E.A. Soliman, IEEE Trans. Antennas Propag. 65 (2017) 4274–4277. [9] M. Yu, X. Zeng, Q. Song, L. Liu, J. Li, J. Clean. Prod. 113 (2016) 973–980. [10] S. Ahmed, F.A. Tahir, A. Shamim, H.M. Cheema, IEEE Antennas Wirel. Propag. Lett. 14 (2015) 1802–1805. [11] H.R. Khaleel, H.M. Al-Rizzo, D.G. Rucker, S. Mohan, IEEE Antennas Wirel. Propag. Lett. 11 (2012) 564–567. [12] S. Wünscher, R. Abbel, J. Perelaer, U.S. Schubert, J. Mater. Chem. C. 2 (2014) 10232–10261. [13] K. Janeczek, G. Kozioł, T. Serzysko, M. Jakubowska, in: Electron. Syst. Integr. Technol. Conf. ESTC 2010 - Proc., 2010, pp. 3–7. [14] J.J. Adams, J.S. Jur, H. Soewardiman, C.A. Muchler, H. Shahariar, Smart Mater. Struct. 27 (2018) 045008. [15] D.Y. Zhang, J. Liu, Y.S. Shi, Y. Wang, H.F. Liu, Q.L. Hu, L. Su, J. Zhu, J. Membr. Sci. 516 (2016) 83–93.