No abstract

Assessment of the cough severity is essential when dealing with respiratory diseases such as chronic obstructive pulmonary disease and COVID‐19. Although a few wearable devices have been reported for cough detection, they mostly rely on microphones, accelerometers, or throat‐fixed flexible sensors, which suffer from key issues including privacy disclosure and speech/motion artifacts. This study presents a chest‐laminated electronic skin (e‐skin) for reliable cough detection. Mixed dumbbell‐like networks and through‐holes are engineered on hard‐to‐stretch composite films for high stretching force sensitivity and sweat permeation, respectively. The e‐skin can effectively reduce speech‐signal and motion artifacts owing to firm adhesion and conformal contact with the chest even on sweaty skin. Experimental results show that the specificity for cough identification is as high as 99.75% through machine learning of automated acoustic analysis, even in the presence of hard‐to‐distinguish daily activities such as throat clearing. The developed chest‐laminated e‐skin is a simple, comfortable, yet reliable method to detect cough for the primary diagnosis of respiratory diseases by extracting subtle acoustic information from cough.

One of the key requirements for MEMS speakers is to increase the sound pressure level (SPL) while keeping the size as small as possible. In this paper we present a MEMS speaker based on piezoelectric bimorph cantilevers that produces a higher SPL than conventional unimorph cantilever speakers. The active diaphragm size is 1.4 × 1.4 mm2. The bimorph cantilevers are connected in parallel to make full use of the actuation voltage. At 1 kHz, the measured SPL reached 73 dB and the peak SPL reached 102 dB at the resonance frequency of 10 kHz in a 711 ear simulator under a driving voltage of 10 Vrms. The total harmonic distortion of the MEMS speaker was less than 3% in the range from 100 Hz to 20 kHz. Although the absolute SPL was not the highest, this work provides a better SPL for all piezoelectric MEMS speakers.