A preliminary study of printed electronics through flexography impression on flexible substrates

[EN] The work is framed within Printed Electronics, an emerging technology for the manufacture of electronic products. Among the different printing methods, the roll-to-roll flexography technique is used because it allows continuous manufacturing and high productivity at low cost. Apart from the process parameters, the ink and the substrate properties are some of the variables associated with the flexographic printing. Specifically, this study investigates the ink penetration, the print uniformity, the adhesion, the fastness, and the electrical behaviour of the same conductive silver ink printed on different flexible substrates through the flexography process. In addition to polymeric and siliconized paper substrates, which are typical used in printed electronics, two substrates were also chosen for the study: woven and nonwoven fabric. Optical, scanning electronic microscope (SEM), 4-point Kelvin and colour fastness to wash and rubbing analyses have been performed. The results concluded that, regarding the conductivity behaviour, porous substrates like textiles and nonwoven fabrics without pre and post treatments do not present acceptable results, whereas polymers or silicone papers do. Nevertheless, woven and nonwoven fabrics are a suitable early option regarding colour fastness to wash instead of thin polymeric and paper substrates that tear at the wash machine. A solution for an optimal printing on textiles would be the surface substrates pre-treatment by applying different chemical compounds that increase the adhesion of the ink on the fabricThis research is part of HYBRID project that is funded by the Conselleria d¿Economia Sostenible, Sectors Productius i Treball, through IVACE. Application No.: IMAMCI/2020/1Rodes Carbonell, AM.; Ferri Pascual, J.; Garcia-Breijo, E.; Bou-Belda, E. (2021). A preliminary study of printed electronics through flexography impression on flexible substrates. Industria Textila. 72(2):133-137. https://doi.org/10.35530/it.072.02.20202413313772

Textile Concentric Ring Electrodes for ECG Recording Based on Screen-Printing Technology

[EN] Among many of the electrode designs used in electrocardiography (ECG), concentric ring electrodes (CREs) are one of the most promising due to their enhanced spatial resolution. Their development has undergone a great push due to their use in recent years; however, they are not yet widely used in clinical practice. CRE implementation in textiles will lead to a low cost, flexible, comfortable, and robust electrode capable of detecting high spatial resolution ECG signals. A textile CRE set has been designed and developed using screen-printing technology. This is a mature technology in the textile industry and, therefore, does not require heavy investments. Inks employed as conductive elements have been silver and a conducting polymer (poly (3,4-ethylenedioxythiophene) polystyrene sulfonate; PEDOT: PSS). Conducting polymers have biocompatibility advantages, they can be used with flexible substrates, and they are available for several printing technologies. CREs implemented with both inks have been compared by analyzing their electric features and their performance in detecting ECG signals. The results reveal that silver CREs present a higher average thickness and slightly lower skin-electrode impedance than PEDOT: PSS CREs. As for ECG recordings with subjects at rest, both CREs allowed the uptake of bipolar concentric ECG signals (BC-ECG) with signal-to-noise ratios similar to that of conventional ECG recordings. Regarding the saturation and alterations of ECGs captured with textile CREs caused by intentional subject movements, silver CREs presented a more stable response (fewer saturations and alterations) than those of PEDOT: PSS. Moreover, BC-ECG signals provided higher spatial resolution compared to conventional ECG. This improved spatial resolution was manifested in the identification of P1 and P2 waves of atrial activity in most of the BC-ECG signals. It can be concluded that textile silver CREs are more suitable than those of PEDOT: PSS for obtaining BC-ECG records. These developed textile electrodes bring the use of CREs closer to the clinical environment.Grant from the Ministerio de Economia y Competitividad y del Fondo Europeo de Desarrollo Regional. DPI2015-68397-R (MINECO/FEDER). This work was also supported by the Spanish Government/FEDER funds (grant number MAT2015-64139-C4-3-R (MINECO/FEDER)).Lidon-Roger, JV.; Prats-Boluda, G.; Ye Lin, Y.; Garcia Casado, FJ.; Garcia-Breijo, E. (2018). Textile Concentric Ring Electrodes for ECG Recording Based on Screen-Printing Technology. Sensors. 18(1):300-314. https://doi.org/10.3390/s18010300S30031418

An investigation into the fabrication parameters of screen-printed capacitive sensors on e-textiles

[EN] The design and development of textile-based capacitive sensors requires the implementation of textile capacitors with a determined capacitance. One of the main techniques to obtain these sensors is the screen-printing of conductive and dielectric inks on textiles. This paper investigates the fabrication parameters that have the most influence when designing and implementing a screen-printed capacitive sensor. In this work, a textile has been used directly as the dielectric part, influencing sensitively the value of the permittivity and the thickness of the dielectric of the capacitor. These are two fundamental parameters for the estimation of its capacitance. The choice of the conductive ink, its viscosity and solid content, as well as printing parameters, such as printing direction, also impact on the manner for obtaining the electrodes of the capacitive sensor. Although the resulting electrodes do not represent an important parameter for the estimation of the capacitance, it determines the selection of fabrics that can be printed. As a result of the investigation, the paper provides a guideline to choose the materials, such as fabrics or inks, as well as the printing parameters, to implement e-textile applications based on projected capacitive technologies. The experiments carried out on different fabrics and inks have provided results with capacities of less than 60 pF, the limit where the sensors based on capacitive technologies are located.The authors disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and cofounded by ERDF funding from the European Union (Application no. IMAMCI/2019/1). This work was also supported by the Spanish Government/FEDER funds (RTI2018-100910-B-C43) (MINECO/FEDER).Ferri, J.; Llinares Llopis, R.; Moreno, J.; Lidon-Roger, JV.; Garcia-Breijo, E. (2020). An investigation into the fabrication parameters of screen-printed capacitive sensors on e-textiles. Textile Research Journal. 90(15-16):1749-1769. https://doi.org/10.1177/0040517519901016S174917699015-16Gonçalves, C., Ferreira da Silva, A., Gomes, J., & Simoes, R. (2018). Wearable E-Textile Technologies: A Review on Sensors, Actuators and Control Elements. Inventions, 3(1), 14. doi:10.3390/inventions3010014Mostafalu, P., Tamayol, A., Rahimi, R., Ochoa, M., Khalilpour, A., Kiaee, G., … Khademhosseini, A. (2018). Smart Bandage for Monitoring and Treatment of Chronic Wounds. Small, 14(33), 1703509. doi:10.1002/smll.201703509Shi, H., Zhao, H., Liu, Y., Gao, W., & Dou, S.-C. (2019). Systematic Analysis of a Military Wearable Device Based on a Multi-Level Fusion Framework: Research Directions. Sensors, 19(12), 2651. doi:10.3390/s19122651Kim, K., Jung, M., Jeon, S., & Bae, J. (2019). Robust and scalable three-dimensional spacer textile pressure sensor for human motion detection. Smart Materials and Structures, 28(6), 065019. doi:10.1088/1361-665x/ab1adfFerri, J., Perez Fuster, C., Llinares Llopis, R., Moreno, J., & Garcia‑Breijo, E. (2018). Integration of a 2D Touch Sensor with an Electroluminescent Display by Using a Screen-Printing Technology on Textile Substrate. Sensors, 18(10), 3313. doi:10.3390/s18103313De Vos, M., Torah, R., Glanc-Gostkiewicz, M., & Tudor, J. (2016). A Complex Multilayer Screen-Printed Electroluminescent Watch Display on Fabric. Journal of Display Technology, 12(12), 1757-1763. doi:10.1109/jdt.2016.2613906Lin, X., & Seet, B.-C. (2017). Battery-Free Smart Sock for Abnormal Relative Plantar Pressure Monitoring. IEEE Transactions on Biomedical Circuits and Systems, 11(2), 464-473. doi:10.1109/tbcas.2016.2615603Ejupi, A., & Menon, C. (2018). Detection of Talking in Respiratory Signals: A Feasibility Study Using Machine Learning and Wearable Textile-Based Sensors. Sensors, 18(8), 2474. doi:10.3390/s18082474Polanský, R., Soukup, R., Řeboun, J., Kalčík, J., Moravcová, D., Kupka, L., … Hamáček, A. (2017). A novel large-area embroidered temperature sensor based on an innovative hybrid resistive thread. Sensors and Actuators A: Physical, 265, 111-119. doi:10.1016/j.sna.2017.08.030Komazaki, Y., & Uemura, S. (2019). Stretchable, printable, and tunable PDMS-CaCl2 microcomposite for capacitive humidity sensors on textiles. Sensors and Actuators B: Chemical, 297, 126711. doi:10.1016/j.snb.2019.126711Ng, C. L., & Reaz, M. B. I. (2019). Evolution of a capacitive electromyography contactless biosensor: Design and modelling techniques. Measurement, 145, 460-471. doi:10.1016/j.measurement.2019.05.031Ferri, J., Lidón-Roger, J., Moreno, J., Martinez, G., & Garcia-Breijo, E. (2017). A Wearable Textile 2D Touchpad Sensor Based on Screen-Printing Technology. Materials, 10(12), 1450. doi:10.3390/ma10121450Atalay, O. (2018). Textile-Based, Interdigital, Capacitive, Soft-Strain Sensor for Wearable Applications. Materials, 11(5), 768. doi:10.3390/ma11050768Yongsang Kim, Hyejung Kim, & Hoi-Jun Yoo. (2010). Electrical Characterization of Screen-Printed Circuits on the Fabric. IEEE Transactions on Advanced Packaging, 33(1), 196-205. doi:10.1109/tadvp.2009.2034536Lee, W. J., Park, J. Y., Nam, H. J., & Choa, S.-H. (2019). The development of a highly stretchable, durable, and printable textile electrode. Textile Research Journal, 89(19-20), 4104-4113. doi:10.1177/0040517519828992Chatterjee, K., Tabor, J., & Ghosh, T. K. (2019). Electrically Conductive Coatings for Fiber-Based E-Textiles. Fibers, 7(6), 51. doi:10.3390/fib7060051Gu, J. F., Gorgutsa, S., & Skorobogatiy, M. (2010). Soft capacitor fibers using conductive polymers for electronic textiles. Smart Materials and Structures, 19(11), 115006. doi:10.1088/0964-1726/19/11/115006Khan, S., Lorenzelli, L., & Dahiya, R. S. (2015). Technologies for Printing Sensors and Electronics Over Large Flexible Substrates: A Review. IEEE Sensors Journal, 15(6), 3164-3185. doi:10.1109/jsen.2014.2375203Zhang, Q., Wang, Y. L., Xia, Y., Zhang, P. F., Kirk, T. V., & Chen, X. D. (2019). Textile‐Only Capacitive Sensors for Facile Fabric Integration without Compromise of Wearability. Advanced Materials Technologies, 4(10), 1900485. doi:10.1002/admt.201900485Mukherjee, P. K. (2018). Dielectric properties in textile materials: a theoretical study. The Journal of The Textile Institute, 110(2), 211-214. doi:10.1080/00405000.2018.1473710Sadi, M. S., Yang, M., Luo, L., Cheng, D., Cai, G., & Wang, X. (2019). Direct screen printing of single-faced conductive cotton fabrics for strain sensing, electrical heating and color changing. Cellulose, 26(10), 6179-6188. doi:10.1007/s10570-019-02526-

A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves

[EN] Developing new types of optimized electrodes for specific biomedical applications can substantially improve the quality of the sensed signals. Concentric ring electrodes have been shown to provide enhanced spatial resolution to that of conventional disc electrodes. A sensor with different electrode sizes and configurations (monopolar, bipolar, etc.) that provides simultaneous records would be very helpful for studying the best signal-sensing arrangement. A 5-pole electrode with an inner disc and four concentric rings of different sizes was developed and tested on surface intestinal myoelectrical recordings from healthy humans. For good adaptation to a curved body surface, the electrode was screen-printed onto a flexible polyester substrate. To facilitate clinical use, it is self-adhesive, incorporates a single connector and can perform dry or wet (with gel) recordings. The results show it to be a versatile electrode that can evaluate the optimal configuration for the identification of the intestinal slow wave and reject undesired interference. A bipolar concentric record with an outer ring diameter of 30 mm, a foam-free adhesive material, and electrolytic gel gave the best results.Grant from the Ministerio de Economia y Competitividad y del Fondo Europeo de Desarrollo Regional. DPI2015-68397-R (MINECO/FEDER).Zena-Giménez, VF.; Garcia Casado, FJ.; Ye Lin, Y.; Garcia-Breijo, E.; Prats-Boluda, G. (2018). A Flexible Multiring Concentric Electrode for Non-Invasive Identification of Intestinal Slow Waves. Sensors. 18(2):396-412. https://doi.org/10.3390/s18020396S39641218

A Wearable Textile 2D Touchpad Sensor Based on Screen-Printing Technology

[EN] Among many of the designs used in the detection of 2D gestures for portable technology, the touchpad is one of the most complex and with more functions to implement. Its development has undergone a great push due to its use in displays, but it is not widely used with other technologies. Its application on textiles could allow a wide range of applications in the field of medicine, sports, etc. Obtaining a flexible, robust touchpad with good response and low cost is one of the objectives of this work. A textile touchpad based on a diamond pattern design using screen printing technology has been developed. This technology is widely used in the textile industry and therefore does not require heavy investments. The developed prototypes were analyzed using a particular controller for projected capacitive technologies (pro-cap), which is the most used in gesture detection. Two different designs were used to obtain the best configuration, obtaining a good result in both cases.This work was supported by Spanish Government/FEDER funds (grant number MAT2015-64139-C4-3-R (Mineco/Feder)). The work presented is also funded by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and co-funded by ERDF funding from the EU. Application No. IMAMCI/2017/1.Ferri Pascual, J.; Lidon-Roger, JV.; Moreno Canton, J.; Martinez, G.; Garcia-Breijo, E. (2017). A Wearable Textile 2D Touchpad Sensor Based on Screen-Printing Technology. Materials. 10(12):1-16. https://doi.org/10.3390/ma10121450S1161012Takamatsu, S., Lonjaret, T., Ismailova, E., Masuda, A., Itoh, T., & Malliaras, G. G. (2015). Wearable Keyboard Using Conducting Polymer Electrodes on Textiles. Advanced Materials, 28(22), 4485-4488. doi:10.1002/adma.201504249McMillan, D., Brown, B., Lampinen, A., McGregor, M., Hoggan, E., & Pizza, S. (2017). Situating Wearables. Proceedings of the 2017 CHI Conference on Human Factors in Computing Systems. doi:10.1145/3025453.3025993Nirjon, S., Gummeson, J., Gelb, D., & Kim, K.-H. (2015). TypingRing. Proceedings of the 13th Annual International Conference on Mobile Systems, Applications, and Services - MobiSys ’15. doi:10.1145/2742647.2742665Rekimoto, J. (s. f.). GestureWrist and GesturePad: unobtrusive wearable interaction devices. Proceedings Fifth International Symposium on Wearable Computers. doi:10.1109/iswc.2001.962092Kim, K., Joo, D., & Lee, K.-P. (2010). Wearable-object-based interaction for a mobile audio device. Proceedings of the 28th of the international conference extended abstracts on Human factors in computing systems - CHI EA ’10. doi:10.1145/1753846.1754070Yoon, S. H., Huo, K., & Ramani, K. (2016). Wearable textile input device with multimodal sensing for eyes-free mobile interaction during daily activities. Pervasive and Mobile Computing, 33, 17-31. doi:10.1016/j.pmcj.2016.04.008Van Heek, J., Schaar, A. K., Trevisan, B., Bosowski, P., & Ziefle, M. (2014). User requirements for wearable smart textiles. Does the usage context matter (medical vs. sports)? Proceedings of the 8th International Conference on Pervasive Computing Technologies for Healthcare. doi:10.4108/icst.pervasivehealth.2014.255179Rogers, J. A., Someya, T., & Huang, Y. (2010). Materials and Mechanics for Stretchable Electronics. Science, 327(5973), 1603-1607. doi:10.1126/science.1182383Fan, J. A., Yeo, W.-H., Su, Y., Hattori, Y., Lee, W., Jung, S.-Y., … Rogers, J. A. (2014). Fractal design concepts for stretchable electronics. Nature Communications, 5(1). doi:10.1038/ncomms4266Bhalla, M. R., & Bhalla, A. V. (2010). Comparative Study of Various Touchscreen Technologies. International Journal of Computer Applications, 6(8), 12-18. doi:10.5120/1097-1433Walker, G. (2012). A review of technologies for sensing contact location on the surface of a display. Journal of the Society for Information Display, 20(8), 413-440. doi:10.1002/jsid.100Pedersen, H. C., Jakobsen, M. L., Hanson, S. G., Mosgaard, M., Iversen, T., & Korsgaard, J. (2011). Optical touch screen based on waveguide sensing. Applied Physics Letters, 99(6), 061102. doi:10.1063/1.3615656Emamian, S., Avuthu, S. G. R., Narakathu, B. B., Eshkeiti, A., Chlaihawi, A. A., Bazuin, B. J., … Atashbar, M. Z. (2015). Fully printed and flexible piezoelectric based touch sensitive skin. 2015 IEEE SENSORS. doi:10.1109/icsens.2015.7370651George, B., Zangl, H., Bretterklieber, T., & Brasseur, G. (2010). A Combined Inductive–Capacitive Proximity Sensor for Seat Occupancy Detection. IEEE Transactions on Instrumentation and Measurement, 59(5), 1463-1470. doi:10.1109/tim.2010.2040910Gunnarsson, E., Karlsteen, M., Berglin, L., & Stray, J. (2014). A novel technique for direct measurements of contact resistance between interlaced conductive yarns in a plain weave. Textile Research Journal, 85(5), 499-511. doi:10.1177/0040517514532158Enokibori, Y., Suzuki, A., Mizuno, H., Shimakami, Y., & Mase, K. (2013). E-textile pressure sensor based on conductive fiber and its structure. Proceedings of the 2013 ACM conference on Pervasive and ubiquitous computing adjunct publication - UbiComp ’13 Adjunct. doi:10.1145/2494091.2494158Wei, Y., Torah, R., Li, Y., & Tudor, J. (2016). Dispenser printed capacitive proximity sensor on fabric for applications in the creative industries. Sensors and Actuators A: Physical, 247, 239-246. doi:10.1016/j.sna.2016.06.005Gorgutsa, S., Gu, J. F., & Skorobogatiy, M. (2011). A woven 2D touchpad sensor and a 1D slide sensor using soft capacitor fibers. Smart Materials and Structures, 21(1), 015010. doi:10.1088/0964-1726/21/1/015010Hamdan, N. A., Heller, F., Wacharamanotham, C., Thar, J., & Borchers, J. (2016). Grabrics. Proceedings of the 2016 CHI Conference Extended Abstracts on Human Factors in Computing Systems - CHI EA ’16. doi:10.1145/2851581.2892529Kim, D.-K. (2010). A Touchpad for Force and Location Sensing. ETRI Journal, 32(5), 722-728. doi:10.4218/etrij.10.1510.007

Screen-printed Organic Electrochemical Transistors for the detection of ascorbic acid in food

[EN] Methods traditionally used for ascorbic acid (AA) detection in food are often expensive and complex, making them unsuitable for day-to-day determinations. In this work, we report on the use of all- PEDOT:PSS Organic Electrochemical Transistors (OECTs) for fast, simple and low-cost determination of AA in food. The performance of these OECTs was tested first with in lab-prepared solutions of AA with different concentrations. The effect of the geometry on the transistors performance for AA sensing was also investigated by comparing the response of two OECTs with different channel and gate areas ratio (g), in terms of current modulation, sensitivity, background signal and limit of detection (LOD). OECTs with smaller gate electrode than the channel (large g) show the best performance for AA sensing: these devices display smaller background signal, higher sensitivity, larger modulation and better LOD value (80.10^-6 M). Since the AA content in food rich in Vitamin C is in the mM range, these transistors can be considered sensitive enough for quantitatively monitoring AA in food. In order to demonstrate the reliability of the proposed sensors in real food samples, the response of these transistors was additionally measured in a commercial orange juice. The amount of AA obtained with the OECTs is in good agreement with that determined by HPLC and with values reported in the literature for orange juices. Furthermore, these OECTs can be considered promising candidates for the selective detection of AA in the presence of other interfering antioxidants.This work was supported by Spanish Government/FEDER funds (grant number MAT2015-64139-C4-3-R (MINECO/FEDER)) and Generalitat Valenciana funds (grant number AICO/2015/103).Contat-Rodrigo, L.; Pérez Fuster, C.; Lidon-Roger, JV.; Bonfiglio, A.; Garcia-Breijo, E. (2017). Screen-printed Organic Electrochemical Transistors for the detection of ascorbic acid in food. Organic Electronics. 45:89-96. https://doi.org/10.1016/j.orgel.2017.02.03789964

Influence of Structure and Composition of Woven Fabrics on the Conductivity of Flexography Printed Electronics

[EN] The work is framed within Printed Electronics, an emerging technology for the manufacture of electronic products. Among the different printing methods, the roll-to-roll flexography technique is used because it allows continuous manufacturing and high productivity at low cost. Nevertheless, the incorporation of the flexography printing technique in the textile field is still very recent due to technical barriers such as the porosity of the surface, the durability and the ability to withstand washing. By using the flexography printing technique and conductive inks, different printings were performed onto woven fabrics. Specifically, the study is focused on investigating the influence of the structure of the woven fabric with different weave construction, interlacing coefficient, yarn number and fabric density on the conductivity of the printing. In the same way, the influence of the weft composition was studied by a comparison of different materials (cotton, polyester, and wool). Optical, SEM, color fastness to wash, color measurement using reflection spectrophotometer and multi-meter analyses concluded that woven fabrics have a lower conductivity due to the ink expansion through the inner part of the textile. Regarding weft composition, cotton performs worse due to the moisture absorption capacity of cellulosic fiber. A solution for improving conductivity on printed electronic textiles would be pre-treatment of the surface substrates by applying different chemical compounds that increase the adhesion of the ink, avoiding its absorption.This work was supported by the Spanish Government/FEDER funds [Ministerio de Economia y Empresa (MINECO)/Fondo Europeo de Desarrollo Regional (FEDER)] under Grant RTI2018-100910-B-C43.Rodes-Carbonell, AM.; Ferri, J.; Garcia-Breijo, E.; Montava-Seguí, I.; Bou-Belda, E. (2021). Influence of Structure and Composition of Woven Fabrics on the Conductivity of Flexography Printed Electronics. Polymers. 13(18):1-17. https://doi.org/10.3390/polym13183165S117131

Comparison of E-Textile Techniques and Materials for 3D Gesture Sensor with Boosted Electrode Design

[EN] There is an interest in new wearable solutions that can be directly worn on the curved human body or integrated into daily objects. Textiles offer properties that are suitable to be used as holders for electronics or sensors components. Many sensing technologies have been explored considering textiles substrates in combination with conductive materials in the last years. In this work, a novel solution of a gesture recognition touchless sensor is implemented with satisfactory results. Moreover, three manufacturing techniques have been considered as alternatives: screen-printing with conductive ink, embroidery with conductive thread and thermosealing with conductive fabric. The main critical parameters have been analyzed for each prototype including the sensitivity of the sensor, which is an important and specific parameter of this type of sensor. In addition, user validation has been performed, testing several gestures with different subjects. During the tests carried out, flick gestures obtained detection rates from 79% to 89% on average. Finally, in order to evaluate the stability and strength of the solutions, some tests have been performed to assess environmental variations and washability deteriorations. The obtained results are satisfactory regarding temperature and humidity variations. The washability tests revealed that, except for the screen-printing prototype, the sensors can be washed with minimum degradation.This work was supported by the Spanish Government/FEDER funds (RTI2018-100910-B-C43) (MINECO/FEDER). The work presented is also funded by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and cofounded by ERDF funding from the EU. Application No.: IMAMCI/2020/1Ferri Pascual, J.; Llinares Llopis, R.; Martinez, G.; Lidon-Roger, JV.; Garcia-Breijo, E. (2020). Comparison of E-Textile Techniques and Materials for 3D Gesture Sensor with Boosted Electrode Design. Sensors. 20(8):1-19. https://doi.org/10.3390/s20082369S11920

A Wearable Textile 3D Gesture Recognition Sensor Based on Screen-Printing Technology

[EN] Research has developed various solutions in order for computers to recognize hand gestures in the context of human machine interface (HMI). The design of a successful hand gesture recognition system must address functionality and usability. The gesture recognition market has evolved from touchpads to touchless sensors, which do not need direct contact. Their application in textiles ranges from the field of medical environments to smart home applications and the automotive industry. In this paper, a textile capacitive touchless sensor has been developed by using screen-printing technology. Two different designs were developed to obtain the best configuration, obtaining good results in both cases. Finally, as a real application, a complete solution of the sensor with wireless communications is presented to be used as an interface for a mobile phone.The work presented is funded by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and cofounded by ERDF funding from the EU. Application No.: IMAMCI/2019/1. This work was also supported by the Spanish Government/FEDER funds (RTI2018-100910-B-C43) (MINECO/FEDER).Ferri Pascual, J.; Llinares Llopis, R.; Moreno Canton, J.; Ibáñez Civera, FJ.; Garcia-Breijo, E. (2019). A Wearable Textile 3D Gesture Recognition Sensor Based on Screen-Printing Technology. Sensors. 19(23):1-32. https://doi.org/10.3390/s19235068S1321923Chakraborty, B. K., Sarma, D., Bhuyan, M. K., & MacDorman, K. F. (2017). Review of constraints on vision‐based gesture recognition for human–computer interaction. IET Computer Vision, 12(1), 3-15. doi:10.1049/iet-cvi.2017.0052Zhang, Z. (2012). 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Low-Temperature Soldering of Surface Mount Devices on Screen-Printed Silver Tracks on Fabrics for Flexible Textile Hybrid Electronics

[EN] The combination of flexible-printed substrates and conventional electronics leads to flexible hybrid electronics. When fabrics are used as flexible substrates, two kinds of problems arise. The first type is related to the printing of the tracks of the corresponding circuit. The second one concerns the incorporation of conventional electronic devices, such as integrated circuits, on the textile substrate. Regarding the printing of tracks, this work studies the optimal design parameters of screen-printed silver tracks on textiles focused on printing an electronic circuit on a textile substrate. Several patterns of different widths and gaps between tracks were tested in order to find the best design parameters for some footprint configurations. With respect to the incorporation of devices on textile substrates, the paper analyzes the soldering of surface mount devices on fabric substrates. Due to the substrate's nature, low soldering temperatures must be used to avoid deformations or damage to the substrate caused by the higher temperatures used in conventional soldering. Several solder pastes used for low-temperature soldering are analyzed in terms of joint resistance and shear force application. The results obtained are satisfactory, demonstrating the viability of using flexible hybrid electronics with fabrics. As a practical result, a simple single-layer circuit was implemented to check the results of the research.This work was supported by the Spanish Government FEDER funds (RTI2018-100910B-C43) (MINECO/FEDER). The work presented is also funded by the Conselleria d'Economia Sostenible, Sectors Productius i Treball, through IVACE (Instituto Valenciano de Competitividad Empresarial) and cofunded by ERDF funding from the EU Stretch Project, application No.: IMAMCA/2022/6.Silvestre, R.; Llinares Llopis, R.; Contat-Rodrigo, L.; Serrano Martínez, V.; Ferri, J.; Garcia-Breijo, E. (2022). Low-Temperature Soldering of Surface Mount Devices on Screen-Printed Silver Tracks on Fabrics for Flexible Textile Hybrid Electronics. Sensors. 22(15):1-23. https://doi.org/10.3390/s22155766123221