Multifunctional Textile Electronic with Sensing, Energy Storing, and Electrothermal Heating Capabilities

A Fabric-Based Strain Sensor with a Microbridge Structure and the Supercapacitor-Powered Integrated Sensing System

Developing fabric-based strain sensors with high sensitivity and stability is in high demand for wearable electronics. Herein, carbon nanotubes (CNTs) and polypyrrole (PPy) are coated on a thermoplastic polyurethane (TPU) fabric as strain sensors. A microbridge structure, in which CNT bridges the stretching-induced cracks, has been designed for the TPU-CNT-PPy strain sensor. The microbridge structure can significantly enhance the electrical resilience, ensuring the improved sensitivity and stability of strain sensors. As a result, our TPU-CNT-PPy strain sensors deliver high sensitivity (GF = 231.5) with a broad working range (150%) and fast response and recovery time (166/195 ms). In addition, our TPU-CNT-PPy could also be used as flexible electrodes of the microsupercapacitors (MSCs) as a power supplier for the integrated sensing system. The TPU-CNT-PPy-based MSCs exhibit a high specific capacitance (460.3 mF cm-2 at 0.5 mA cm-2) and excellent cycling stability (96.69% capacitance retention for 10,000 charge/discharge cycles). Finally, we demonstrated an integrated sensing system using TPU-CNT-PPy as both MSCs and strain sensors, where the current signals of the sensors could be well detected via Bluetooth. This study offers a microbridge strategy to fabricate strain sensors with high sensitivity and stability and develops an integrated sensing system for the actual applications of wearable electronics.

Fabrication of Multi-Layered Paper-Based Supercapacitor Anode by Growing Cu(OH)2 Nanorods on Oxygen Functional Groups-Rich Sponge-Like Carbon Fibers

This work addresses the challenges in developing carbon fiber paper-based supercapacitors (SCs) with high energy density by focusing on the limited capacity of carbon fiber. To overcome this limitation, a sponge-like porous carbon fiber paper enriched with oxygen functional groups (OFGs) is prepared, and Cu(OH)2 nanorods are grown on its surface to construct the SC anode. This design results in a multi-layered carbon fiber paper-based electrode with a specific structure and enhanced capacitance. The Cu(OH)2 @PCFP anode exhibits an areal capacitance of 547.83 mF cm-2 at a current density of 1 mA cm-2 and demonstrates excellent capacitance retention of 99.8% after 10 000 cycles. Theoretical calculations further confirm that the Cu(OH)2 /OFGs-graphite heterostructure exhibits higher conductivity, facilitating faster charge transfer. A solid-state SC is successfully assembled using Ketjen Black@PCFP as the cathode and KOH/PVA as the gel electrolyte. The resulting device exhibits an energy density of 0.21 Wh cm-2 at 1.50 mW cm-2 , surpassing the performance of reported Cu(OH)2 SCs. This approach, combining materials design with an understanding of underlying mechanisms, not only expands the range of electrode materials but also provides valuable insights for the development of high-capacity energy storage devices.

In Situ Spray Polymerization of Conductive Polymers for Personalized E-textiles

E-textiles, also known as electronic textiles, seamlessly merge wearable technology with fabrics, offering comfort and unobtrusiveness and establishing a crucial role in health monitoring systems. In this field, the integration of custom sensor designs with conductive polymers into various fabric types, especially in large areas, has presented significant challenges. Here, we present an innovative additive patterning method that utilizes a dual-regime spray system, eliminating the need for masks and allowing for the programmable inscription of sensor arrays onto consumer textiles. Unlike traditional spray techniques, this approach enables in situ, on-the-fly polymerization of conductive polymers, enabling intricate designs with submillimeter resolution across fabric areas spanning several meters. Moreover, it addresses the nozzle clogging issues commonly encountered in such applications. The resulting e-textiles preserve essential fabric characteristics such as breathability, wearability, and washability while delivering exceptional sensing performance. A comprehensive investigation, combining experimental, computational, and theoretical approaches, was conducted to examine the critical factors influencing the operation of the dual-regime spraying system and its role in e-textile fabrication. These findings provide a flexible solution for producing e-textiles on consumer fabric items and hold significant implications for a diverse range of wearable sensing applications.

Radiative cooling and anisotropic wettability in E-textile for comfortable biofluid monitoring

Long-term wearing comfort is essential for future advanced electronic textiles (e-textiles). Herein, we fabricate a skin-comfortable e-textile for long-term wearing experience on human epidermis. Such e-textile was simply fabricated through two different dip coating methods and single-side air plasma treatment, which couples radiative thermal and moisture management for biofluid monitoring. The silk-based substrate with improved optical properties and anisotropic wettability can provide a temperature drop of 1.4 °C under strong sunlight. Moreover, the anisotropic wettability of the e-textile can provide a dryer skin microenvironment by comparing with traditional fabric. The fiber electrodes weaving into the inner side of the substrate can noninvasively monitor multiple sweat biomarkers (i.e., pH, uric acid, and Na+). Such a synergistic strategy may pave a new path to design next-generation e-textiles with significantly improved comfort.

Recent Progress of Energy-Storage-Device-Integrated Sensing Systems

With the rapid prosperity of the Internet of things, intelligent human-machine interaction and health monitoring are becoming the focus of attention. Wireless sensing systems, especially self-powered sensing systems that can work continuously and sustainably for a long time without an external power supply have been successfully explored and developed. Yet, the system integrated by energy-harvester needs to be exposed to a specific energy source to drive the work, which provides limited application scenarios, low stability, and poor continuity. Integrating the energy storage unit and sensing unit into a single system may provide efficient ways to solve these above problems, promoting potential applications in portable and wearable electronics. In this review, we focus on recent advances in energy-storage-device-integrated sensing systems for wearable electronics, including tactile sensors, temperature sensors, chemical and biological sensors, and multifunctional sensing systems, because of their universal utilization in the next generation of smart personal electronics. Finally, the future perspectives of energy-storage-device-integrated sensing systems are discussed.