Development of a face mask attachable wireless piezoresistive nanocomposite sensor for monitoring respiratory health

Abstract

A piezoresistance-based stretchable nanocomposite strip that can be attached to a face mask was developed. The wireless acquisition of respiratory activities using this nanocomposite strip was demonstrated. A polyurethane/functionalized-multiwall carbon nanotube (PU/f-MWCNT) nanocomposite was prepared by functionalizing MWCNTs and integrating them with PU. The functionalization of MWCNTs was confirmed using FTIR analysis. A study on the effect of carboxylic functionalization of MWCNTs on the dispersion of MWCNTs in the PU matrix was carried out by measuring resistance at different regions of the nanocomposite. It was observed that carboxylic functionalized CNTs dispersed uniformly in the PU matrix compared with non-functionalized MWCNTs. The electrical percolation threshold for the nanocomposites was achieved at an f-MWCNT concentration of 1.8%. The nanocomposites were further used to fabricate a wearable sensor for integration with a sensor-enabled mask, which could acquire respiratory patterns in real-time. The sensor can identify respiratory patterns, such as the mean time required to complete one respiratory cycle. In normal breathing, the average time to complete one respiratory cycle was 3.44 seconds, with a pause of 0.73 seconds between consecutive cycles. However, for slow breathing patterns, the time required to complete one cycle increased to 7.05 seconds, and the hold time between cycles increased to 2 seconds. Identifying respiratory signal patterns helps identify inhalation and exhalation durations, which thereby helps identify dysfunctional respiration. The developed sensor-based mask is suitable for continuous remote monitoring of respiratory disorders outside the clinical setting. Continuous monitoring of respiratory health can be beneficial for timely intervention or for monitoring respiratory illness and recovery.