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

Abstract

Flexible gas sensors play an indispensable role in diverse applications spanning from environmental monitoring to portable medical electronics. Full wearable gas monitoring system requires the collaborative support of high‐performance sensors and miniaturized circuit module, whereas the realization of low power consumption and sustainable measurement is challenging. Here, a self‐powered and reusable all‐in‐one NO2 sensor is proposed by structurally and functionally coupling the sensor to the battery, with ultrahigh sensitivity (1.92%/ppb), linearity (R2 = 0.999), ultralow theoretical detection limit (0.1 ppb), and humidity immunity. This can be attributed to the regulation of the gas reaction route at the molecular level. The addition of amphiphilic zinc trifluoromethanesulfonate (Zn(OTf)2) enables the H2O‐poor inner Helmholtz layer to be constructed at the electrode–gel interface, thereby facilitating the direct charge transfer process of NO2 here. The device is then combined with a well‐designed miniaturized low‐power circuit module with signal conditioning, processing and wireless transmission functions, which can be used as wearable electronics to realize early and remote warning of gas leakage. This study demonstrates a promising way to design a self‐powered, sustainable, and flexible gas sensor with high performance and its corresponding wireless sensing system, providing new insight into the all‐in‐one system of gas detection.

Micropyramidal Flexible Ion Gel Sensor for Multianalyte Discrimination and Strain Compensation

“…As shown in Figure S9, the response curves of the sensor to toluene and ammonia can be expressed as the linear regression mathematical equation of y = 3.4098 x + 6.4001 and y = 1.6039 x – 1.1518, respectively, where y and x are the response of the sensor and the concentration of gases, respectively. The limit of detection (LOD) can be determined as LOD = 3 × (No/S), where No = 0.0392 and S are the noise and the slope of the curve, respectively (Figure S9, Table S1, and Supporting text). , The calculated LODs of the sensor in toluene and ammonia detection are 34 and 73 ppb, respectively. These susceptible responses of the ionic gel sensor indicate the capability of detecting gases in the environment.…”

“…The limit of detection (LOD) can be determined as LOD = 3 × (No/S), where No = 0.0392 and S are the noise and the slope of the curve, respectively (Figure S9, Table S1, and Supporting text). 54,55 The calculated LODs of the sensor in toluene and ammonia detection are 34 and 73 ppb, respectively. These susceptible responses of the ionic gel sensor indicate the capability of detecting gases in the environment.…”

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.…”

A highly stretchable and sensitive strain sensor for lip-reading extraction and speech recognition

“…9–13 Many high-performance (high sensitivity and selectivity) flexible strain sensors have been reported, such as graphene-based flexible sensors, conducting hydrogel-based flexible sensors, and fiber-based smart sensors. 14–20 However, most wearable strain sensors are capable of tracking individual speech information through the vocal cord vibration of the speaker. 21–25 For instance, Gao et al .…”

“…[9][10][11][12][13] Many high-performance (high sensitivity and selectivity) flexible strain sensors have been reported, such as graphene-based flexible sensors, conducting hydrogel-based flexible sensors, and fiberbased smart sensors. [14][15][16][17][18][19][20] However, most wearable strain sensors are capable of tracking individual speech information through the vocal cord vibration of the speaker. [21][22][23][24][25] For instance, Gao et al 22 fabricated a strain sensor based on fragmented carbonized melamine sponges and attached the strain sensor to the epidermis 2 cm below the throat of the tester to record the specific changes in the a Key Laboratory of Optical Field Manipulation of Zhejiang Province, School of electrical signal when the tester read the letters ''E'', ''C'', ''U'', ''S'' and ''T'', which showed excellent pronunciation recognition ability.…”