A low power wearable respiration monitoring sensor using pyroelectric transducer

This paper presents a fully integrated low-power wearable respiration monitoring system using a pyroelectric transducer. Many chronic respiratory diseases such as asthma and apnea are leading causes of death worldwide which are even more critical for premature neonatal infants. Currently, the diagnosis of apnea requires the infants to go through overnight clinical sleep analysis, also known as polysomnography for 12 to 24-hour period. During this process numerous sensors are attached to the sensitive skin of the infants resulting in irritation and inconvenience. To overcome this problem a novel point-of-care respiration monitoring system has been proposed. At the front-end of the sensor a PVDF (Polyvinylidene Fluoride) based pyroelectric transducer is used which could be placed under the nasal cavity or inside a cannula of the subject. The charge generated by the transducer due to the nasal air flow is then converted to a proportional voltage signal by an operational transconductance amplifier (OTA) based charge amplifier. The subsequent signal processing blocks detect and process the signal coming out of the charge amplifier if it lies within the voltage range that corresponds to an apneic event. Once the signal is detected an alarm signal is generated indicating the occurrence of an apneic event. The light-weight design and smaller footprint of the transducer as well as the integrated devices make it suitable as a wearable sensor for non-invasive respiration monitoring. A prototype device with the integrated circuit fabricated using 0.5μm CMOS process is presented in the paper which can prevent many major disorders that can lead to neonatal mortality.