High‐Performance Strain Sensors Based on Organohydrogel Microsphere Film for Wearable Human–Computer Interfacing

Abstract

Stretchable hydrogel-based strain sensors suffer from limited sensitivity, which urgently requires further breakthroughs for precise and stable human-computer interaction. Here, an efficient microstructural engineering strategy is proposed to significantly enhance the sensitivity of hydrogel-based strain sensors by sandwiching an emulsion-polymerized polyacrylamide organohydrogel microsphere membrane between two Ecoflex films, which are accompanied by crack generation and propagation effects upon stretching. Consequently, the as-developed strain sensor exhibits ultrahigh sensitivity (gauge factor (GF) of 1275), wide detection range (100% strain), low hysteresis, ultralow detection limit (0.05% strain), good fatigue resistance, and low fabrication cost. In addition, the sensor features good water, dehydration, and frost resistance, enabling real-time strain monitoring in various complex conditions due to the encapsulation of Ecoflex film and the addition of glycerol and KCl. Through further structural manipulation, the device achieves superior response to tiny strains, with a GF value of 98.3 in the strain range of less than 1.5%. Owing to the high strain sensing performance, the sensor is able to detect various human activities from swallowing to finger bending even under water. On this basis, a wireless sensing system with apnea warning and single-channel gesture recognition capabilities is successfully demonstrated, demonstrating its great promise as wearable electronics.

Engineering Smart Composite Hydrogels for Wearable Disease Monitoring

“…By adjusting the internal components of hydrogels or constructing unique hydrogel structures through hydrogel engineering, smart composite hydrogels with a variety of properties, such as enhanced mechanical properties, electrical conductivity, self-healing, stimuli responsiveness, and self-adhesion, can be obtained. Smart composite hydrogels, which possess excellent physicochemical properties, have great potential in wearable sensing fields [ 204 , 205 ]. Wearable health monitoring devices based on smart composite hydrogels have been widely used in health care scenarios such as physiological state monitoring, wound monitoring, and disease diagnosis.…”

Efficient fabrication of highly stretchable and ultrasensitive thermoplastic polyurethane/carbon nanotube foam with anisotropic pore structures for human motion monitoring

“…Compared with solid exible strain sensors, foam-shaped exible strain sensors have higher sensitivities with lower detection ranges. 24,[48][49][50][51][52] For instance, the hydrophobic strain sensor with a coated layer of reduced graphene oxide (rGO) sheets has a wide detection range of 400 but a low sensitivity of 140. 45 The working range of hydrogel/MXene reaches up to 600% but the sensitivity is only 3.93.…”

A Self‐Powered, Rechargeable, and Wearable Hydrogel Patch for Wireless Gas Detection with Extraordinary Performance

“…The further development of the Internet of Things (IoT) requires the integration of a large number of sensors, resulting in enormous power consumption. [21][22][23][24][25] The traditional sensor is powered by a rigid and bulky external power supply, which not only leads to the increase of the overall size of the system, but also greatly sacrifices the portability and comfort of the device. For maximum power consumption reduction and longlasting operation as a wearable device, self-powered characteristics are expected to be introduced into the sensor to realize spontaneous data acquisition and simplify the circuit modules.…”