Well-defined in-textile photolithography towards permeable textile electronics

Abstract

Textile-based wearable electronics have attracted intensive research interest due to their excellent flexibility and breathability inherent in the unique three-dimensional porous structures. However, one of the challenges lies in achieving highly conductive patterns with high precision and robustness without sacrificing the wearing comfort. Herein, we developed a universal and robust in-textile photolithography strategy for precise and uniform metal patterning on porous textile architectures. The as-fabricated metal patterns realized a high precision of sub-100 µm with desirable mechanical stability, washability, and permeability. Moreover, such controllable coating permeated inside the textile scaffold contributes to the significant performance enhancement of miniaturized devices and electronics integration through both sides of the textiles. As a proof-of-concept, a fully integrated in-textiles system for multiplexed sweat sensing was demonstrated. The proposed method opens up new possibilities for constructing multifunctional textile-based flexible electronics with reliable performance and wearing comfort.

Fig. 1. In-textile photolithography for conductive metal patterns in fabrics.

a Schematic illustration showing the development of textile electronics by in-textile photolithography technology. b Digital image of the Cu PCB circuit patterned in polyester fabric. Inset is the high-resolution image showing the Cu tracks in the fabric. c SEM image showing the boundary of the Cu pattern in polyester fabric. d Cross-sectional SEM image showing the boundary of the Cu pattern in polyester fabric. The numbers of experimental repetitions of c and d were five times, respectively. e Digital image showing the water vapor permeability and softness of the fabric patterned with Cu patterns. f Digital image of the Ag PCB circuit patterned in polyester fabric. g Digital image of the Ni interdigital electrodes with different scales patterned in polyester fabric. h Digital image of the Cu sensing electrode arrays patterned in glass-fiber fabric. i Digital image of the Ni electrode patterns in non-woven PP fabric.

Fig. 2. Characterization of well-defined and conductive metal patterns in textiles.

a Optical image (left), cross-sectional schematic diagram (top right), and SEM image (bottom right) of the Cu pattern fabricated by the in-textile photolithography method. b Optical image (left), cross-sectional schematic diagram (top right), and SEM image (bottom right) of the Cu pattern fabricated by on-textile patterning method (screen printing). c Comparison of water vapor and air permeability of the fabrics coated with Cu made by the in-textile photolithography method and the on-textile patterning method. Error bars represent the s.d. of the mean from three fabrics coated with Cu. d Comparison of resistance changes (R/R₀) of the Cu patterns made by the in-textile photolithography method and on-textile patterning method. Inset is the digital image showing the flexibility of the Cu patterns made by two methods. e Linear resistance of the Cu patterns as a function of the patterning resolution. Error bars represent the s.d. of the mean from three Cu patterns. f Schematic diagram of the single-sided UV exposure (left) and optical images of the face side and back side of the Cu pattern made by in-textile photolithography (right). g Schematic diagram of the double-sided UV exposure (left) and optical images of the face side and back side of the Cu pattern made by in-textile photolithography (left). h Linear resistance of the Cu patterns as a function of the patterning resolution. Error bars represent the s.d. of the mean from three Cu patterns. i SEM images of the Polyester_0.90, Polyester_0.94, and Polyester_0.98 fabrics. 0.90, 0.94, and 0.98 are the fabric cover factors of the corresponding fabrics. j Linear resistance of the Cu patterns as a function of patterning resolution. Error bars represent the s.d. of the mean from three Cu patterns. k SEM images showing the precise Cu pattern with 100 µm linewidth (left) and 80 µm interspace between Cu patterns (right) in Polyester_0.98 fabrics.

Fig. 3. High-performance electronics enabled by robust and well-defined conductive metal patterns.

a Tensile property of the commercial polyester fabric and polyester fabric after in-textile photolithography. b Resistance of the Cu patterns with different linewidths in polyester fabric during the 10,000-cycle bending test (bending radius: 4.4 mm). c Resistance changes of the Cu patterns with and without additional Au deposition upon 20 washing cycles. Error bars represent the s.d. of the mean from five Cu patterns. d Resistance of the interconnects during 180 times crumpling test. e Resistance upon 20 washing cycles (encapsulated with Ecoflex and measured by connecting the interconnects to 0 Ω resistors). f Cyclic voltammetry curves of the micro-supercapacitors made with interdigital Ni electrodes with different linewidths. MnO₂ is the electrochemically active material. g Areal capacitance of the micro-supercapacitors with different linewidths. Insets are digital images showing the electrode arrays of the micro-supercapacitors with different linewidths. h Digital images of the double-sided wearable temperature monitoring patch with in-situ alarming function based on well-defined and double-sided Cu pattern in polyester fabric.

Fig. 4. Fabrication and performance evaluation of the multiplexed biosensor array for sweat monitoring.

a Schematic illustration showing the fabrication process of the biosensor array in fabric. b Digital image of as-prepared biosensor array in fabric. c–g Sensing performance of as-made pH, Na⁺, K⁺, glucose, and lactate sensors.

Fig. 5. Design and on-body application of the integrated in-textile headband.

a Digital image of the in-textile headband integrated with multiplexed sensing arrays and data analysis transmission circuit. b The logic flow of the in-textile headband. c Digital image showing in-situ sweat monitoring of the in-textile headband during exercise (the headband is mounted on the forehead). d Custom-designed mobile application for real-time and continuous biomarker sensing. e Representative real-time in-situ sweat biomarkers concentration monitoring during endurance cycling with ex-situ validation via analytical tools (pH meter, ICP-MS, and HPLC).