Polymeric piezoresistive airflow sensor to monitor respiratory patterns

Abstract

Monitoring human respiratory patterns is of great importance as it gives essential information for various medical conditions, e.g. sleep apnoea syndrome and chronic obstructive pulmonary disease and asthma, etc. Herein, we have developed a polymeric airflow sensor based on nanocomposites of vertically grown graphene nanosheets (VGNs) with polydimethylsiloxane (PDMS) and explored their applications in monitoring human respiration. The sensing performance of the VGNs/PDMS nanocomposite was characterized by exposing to a range of airflow rates (20–130 l min −1 ), and a linear performance with high sensitivity and low response time (mostly below 1 s) was observed. To evaluate the experimental results, finite-element simulation models were developed in the COMSOL Multiphysics package. The piezoresistive properties of VGNs/PDMS thin film and fluid–solid interaction were thoroughly studied. Laser Doppler vibrometry measures of sensor tip displacement closely approximated simulated deflection results and validated the dynamic response of the sensor. By comparing the proposed sensor and some other airflow sensors in the literature, it is concluded that the VGNs/PDMS airflow sensor has excellent features in terms of sensor height, detection range and sensitivity. The potential application of the VGNs/PDMS airflow sensor in detecting the respiration pattern of human exercises like walking, jogging and running has been demonstrated.

A Robust Bridge‐Type Airflow Sensor Based on Flexible Superhydrophobic Carbon Nanotube Fiber Thin Films

“…j) Comparison of limit of detection and response time between the CNTF‐PPPS‐1 airflow sensor and airflow sensors reported in references. [ 31,37–40,26,41–45 ] (Note: The negative sign in (R‐R 0 )/R 0 value represents only the direction of resistance change, while negative sign indicates the decrease of resistance)…”

“…j) Comparison of limit of detection and response time between the CNTF-PPPS-1 airflow sensor and airflow sensors reported in references. [31,[37][38][39][40]26,[41][42][43][44][45] (Note: The negative sign in (R-R 0 )/R 0 value represents only the direction of resistance change, while negative sign indicates the decrease of resistance) the surface of CNTF-PPPS-1, water droplets bounced back and separated from the surface immediately. The information above articulates the macroscopic phenomena of the movement of water droplets on the surface of CNTF and CNTF-PPPS-1.…”

“…i) Sensing curve of 600 times of airflow on/off switch cycles measured by the CNTF-PPPS-1 sensor at a airflow velocity of 2 m s −1 , 𝛼 = 90°. j) Comparison of limit of detection and response time between the CNTF-PPPS-1 airflow sensor and airflow sensors reported in references [31,[37][38][39][40]26,[41][42][43][44][45]. (Note: The negative sign in (R-R 0 )/R 0 value represents only the direction of resistance change, while negative sign indicates the decrease of resistance)…”

Recent Progress in Long-Term Sleep Monitoring Technology

“…Teichtahl et al used thermistors and nasal pressure sensors to analyze whether humans were breathing and to assess sleep apnea well [ 168 ]. In 2021, Moshizi et al prepared nano-complex airflow sensors by growing graphene nanosheets on the surface of PDMS with good sensitivity and linearity [ 169 ]. NP thermistor is a common respiratory detection sensor.…”

A Low-Cost Flexible Perforated Respiratory Sensor Based on Platinum for Continuous Respiratory Monitoring

“…At present, the sensing mechanisms of respiratory sensors mainly include temperature, humidity, airflow, stress and strain [ 13 , 14 , 15 ]. Polysomnography (PSG) is commonly used in the sleep examination department of hospitals to manifest sleep respiratory signals and other electrophysiological signals [ 16 ].…”