A Humidity‐Resistant, Sensitive, and Stretchable Hydrogel‐Based Oxygen Sensor for Wireless Health and Environmental Monitoring

Abstract

Highly sensitive and wearable gas sensors are highly demanded on account of their widespread application in health and environmental monitoring. However, the sensing performance of conventional room‐temperature gas sensors are prone to fluctuate or even fail under changing humidity, temperature or putting into water, thus severely limiting their practical applications. Herein, a porous elastomer‐encapsulated hydrogel‐based oxygen sensor is designed with impressive room‐temperature sensing performance under various environmental conditions, including high precision (at ppm level), wide detection range (from 5 ppm to 90% O2), excellent repeatability, selectivity, long‐term stability, breathability, and waterproofing. The hydrophobic elastomer film prevents the water molecules from intruding and evaporating to a great extent, making the device resistant to humidity interference and applicable to underwater operation. Benefiting from the intrinsic stretchability of both hydrogel and elastomer films and their strong interfacial bonding, the final device can be stretched up to 100% strain. By integrating the sensor with a wireless circuit module, a wearable/portable oxygen sensing system for real‐time monitoring of health and environment is demonstrated, realizing timely and convenient assessment of respiratory rate, tissue oxygen, ambient oxygen, and dissolved oxygen.

Gradiently Foaming Ultrasoft Hydrogel with Stop Holes for Highly Deformable, Crack‐Resistant and Sensitive Conformal Human‐Machine Interfaces

“…Up to now, numerous hydrogel‐based sensors have been developed to detect electrophysiological signals or capture human motion and then convert this information into instructions for robotic control. [ 18–21 ] However, the challenges in HMI applications of hydrogel sensors remain to simultaneously achieve ultrasoftness for conformal wearing with good comfort, high mechanical robustness for repetitive and crack‐resistant deformation, and improved sensitivity for precise acquisition of human motion. The softness of hydrogels is typically quantified by the Young's modulus and tuned in virtue of reducing polymer concentration and cross‐link density; nevertheless, their mechanical robustness is unavoidably compromised.…”

Facile fabrication of dual-conductivity, humidity-responsive single-layer membranes: towards advanced applications in sensing, actuation, and energy generation

“…A novel category of intelligent responsive actuators has emerged, 1 showcasing the ability to directly convert various environmental stimuli, such as heat, temperature, light, electricity, and humidity, into mechanical movements without the need for an energy supply system. These innovative materials have found significant applications in diverse fields, [2][3][4][5] including soft robotics, [6][7][8] wearable electronics, [9][10][11][12] environment-triggered sensors, 13,14 health monitoring, [15][16][17] non-contact switches 18,19 and power generation. 20 Among them there has been enormous interest in humidity-driven actuators since wet gases, such as water vapors or humidity in the atmosphere, can be employed as a huge renewable source for energy conversion with minimal environmental impact.…”

Anisotropic Elastomer Ionomer Composite-Based Strain Sensors: Achieving High Sensitivity and Wide Detection for Human Motion Detection and Wireless Transmission

“…In recent years, the burgeoning interest in flexible wearable sensors has been remarkable, driven by their promising applications in personal health monitoring, − human motion detection, − artificial skin, , and soft robots. , Among the various types of wearable sensors, resistive-type strain sensors are competitive due to their simple fabrication and high sensing performance. , Typically, a strain sensor integrates soft elastomers as supportive materials and conductive components as sensing elements to achieve mechanoelectrical conversion. Despite the myriad of sensors based on conducting networks aimed at enhancing sensor performance, current designs predominantly concentrate on detecting uniaxial stimuli, limiting their applicability in discerning complex multidimensional strains associated with motions characterized by multiple degrees of freedom.…”