Self-Healing, Self-Adhesive and Stable Organohydrogel-Based Stretchable Oxygen Sensor with High Performance at Room Temperature

Highlights

• The organohydrogel-based O ₂ sensor features full concentration detection range (0-100%), ultralow limit of detection (5.7 ppm), high sensitivity (0.2%/ppm), excellent selectivity, tunable response/recovery speeds, good linearity, and room-temperature operation.

• The oxygen sensor can work normally under various extreme environmental conditions, such as low (below −18 °C) and high (above 40 °C) temperatures, dry (11.3% RH), and humid (90.5% RH) environments.

• An electrochemical reaction-based mechanism is proposed to elucidate the oxygen sensing behavior of ion-conducting organohydrogel.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40820-021-00787-0.

Abstract

With the advent of the 5G era and the rise of the Internet of Things, various sensors have received unprecedented attention, especially wearable and stretchable sensors in the healthcare field. Here, a stretchable, self-healable, self-adhesive, and room-temperature oxygen sensor with excellent repeatability, a full concentration detection range (0-100%), low theoretical limit of detection (5.7 ppm), high sensitivity (0.2%/ppm), good linearity, excellent temperature, and humidity tolerances is fabricated by using polyacrylamide-chitosan (PAM-CS) double network (DN) organohydrogel as a novel transducing material. The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy. Compared with the pristine hydrogel, the DN organohydrogel displays greatly enhanced mechanical strength, moisture retention, freezing resistance, and sensitivity to oxygen. Notably, applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor. Furthermore, the response to the same concentration of oxygen before and after self-healing is basically the same. Importantly, we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments. The organohydrogel oxygen sensor is used to monitor human respiration in real-time, verifying the feasibility of its practical application. This work provides ideas for fabricating more stretchable, self-healable, self-adhesive, and high-performance gas sensors using ion-conducting organohydrogels.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40820-021-00787-0.