Wireless Passive Time-of-Flight Respiratory MEMS Flow Rate Sensor

Abstract

Here we present the first instance of passive wireless MEMS flow rate sensor designed to measure respiratory flow rate and profile using the time-of-flight sensing modality without the need for battery or on-sensor circuits. With a footprint of only 7.2cm2, the sensor can measure human respiratory rate and flow when placed close to the nasal airway using an excitation antenna that transmits an average power of ∼5mW at a ∼75cm distance. To facilitate the time-of-flight sensor, two low loss, high quality factor TPoS MEMS resonators are placed ∼1cm apart and are connected to a small (3.8cm2) planar ground antenna. We were able to measure flow rate and respiration profile of human subject from a distance of 20cm from the base transceiver. In addition to flow rate, we were capable of accurately tracking the respiration profile of the patient and successfully detecting short cessation of breathing events commonly used in diagnosing sleep apnea.