A breathable, waterproof and battery-free wearable e-nose with high flexibility based on MEMS gas sensors for accurate identification of volatile aromatic hydrocarbons

Abstract

Benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS) are harmful gases indoors and in the cabin. Electronic nose (e-nose) technology has shown great potential in detecting BTEXS. However, to maintain the normal operation of the e-nose and improve the recognition accuracy, it often employs a large array of metal oxide semiconductor (MOS) gas sensors, along with extensive signal processing circuits and high-power solid-state batteries. The bulky structure makes it difficult for the e-nose to realize the portable real-time detection of BTEXS. Herein, a breathable, waterproof, battery-free, and highly flexible wearable e-nose (BWBFW e-nose) is fabricated for BTEXS detections. In detail, we first prepare a combination scheme of n-type and p-type MOS for forming four MEMS gas sensors, exhibiting differentiated response characteristics. Subsequently, a wireless supply module and a wireless signal processing module are designed on a flexible porous circuit board. Then, a waterproof and breathable membrane by electrospinning was adopted to encapsulate the flexible circuit board, endowing the e-nose with high safety. Finally, accurate identification and low-error concentration prediction of BTEXS are achieved with the help of a 1D Convolutional Neural Network (1DCNN) algorithm. We believe the e-nose reported here will shed new light on the design of new devices for detecting BTEXS.