Wearable healthcare systems require skin‐adhering electrodes that allow maximal comfort for patients as well as an electronics system to enable signal processing and transmittance. Textile‐based electronics, known as “e‐textiles,” is a platform technology that allows comfort for patients. Here, two‐layered e‐textile patches are designed by controlled permeation of Ag‐particle/fluoropolymer composite ink into a porous textile. The permeated ink forms a cladding onto the nanofibers in the textile substrate, which is beneficial for mechanical and electrical properties of the e‐textile. The printed e‐textile features conductivity of ≈3200 S cm−1, whereas 1000 cycles of 30% uniaxial stretching causes the resistance to increase only by a factor of ≈5, which is acceptable in many applications. Controlling over the penetration depth enables a two‐layer design of the e‐textile, where the sensing electrodes and the conducting traces are printed in the opposite sides of the substrate. The formation of vertical interconnected access is remarkably simple as an injection from a syringe. With the custom‐developed electronic circuits, a surface electromyography system with wireless data transmission is demonstrated. Furthermore, the dry e‐textile patch collects electroencephalography with comparable signal quality to commercial gel electrodes. It is anticipated that the two‐layered e‐textiles will be effective in healthcare and sports applications.

Solid-state potassium ion selective electrode (K + ISE) has been the most studied chemical sensors due to its practical importance in biomedical applications. One of the major obstacles that prevented widespread use of solid-state K + ISE has been output potential drift problem. In this paper, we developed an electrochemical sensing unit in which working, counter, and reference electrodes are integrated in a single plane as all-solid-state form. In order to mitigate the output potential drift, a polyaniline intermediate layer and salt-saturated polyvinylebutyral top coating are introduced in the working and reference electrodes, respectively. Using cyclic voltammetry (CV), uniform layers of polyaniline are deposited on carbon electrode, as confirmed by scanning electron microscope observation. Potentiometry and electrochemical impedance spectroscopy measurement on our K + ISE show high sensitivity (60.5 mV/decade), low concentration for the limit of detection (10 −5.8 M), and large range of linear detection (10 −5 − 1 M), and superior selectivity of K + ISE against NH + 4 , Na + , Mg 2+ , Ca 2+ , and Fe 3+. With its high potential to be miniaturized, we foresee that our solid-state K + ISE will motivate the future applications in microdevices for clinical analysis, agricultural, and environmental applications.

E-textiles, electronics-integrated textiles, require stretchable interconnects with mechanical and electrical reliability over repeated deformation cycles. Whereas elastomers filled with conductive metallic particles have shown promises for e-textiles, conductive inks printed at the top of the textile substrate are prone to suffer brittleness that leads to failure. Here, we report that controlled permeation of silver particle filled fluoroelastomer ink can indeed strengthen nanofibrous textile substrates in terms of ultimate strain and stress, resulting in a reliable electrical conduction over harsh deformation cycles. The permeated ink forms a cladded-layer on the surface of polyurethane nanofiber strands, where the cladded-layer is intrinsically stronger and tougher than the nanofiber substrate. Selecting a solvent that swells the nano-textile substrate can facilitate deep permeation. Pressing treatment changes the internal structure drastically, which results in a further improvement of mechanical properties of the printed nano-textile. As a result, the strain-to-failure of the e-textile increases ∼3 times and the initial conductivity is 3399 S cm −1 . The resistance increases less than the factor of 2.5 over 4000 cycles of 20% uniaxial strain. The high performance of the stretchable interconnects envisions wearable healthcare and internet-of-things applications.

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