Development of a Reliable Spiroximeter for Covid-19 Patients’ Telemonitoring

Abstract

This paper presents a non-invasive device, for assessing two vital COVID-19 related parameters: respiratory function and patients’ blood oxygenation in a simple manner, capable of detecting early symptoms, thus enabling proactive treatment rather than responsive. Its operation is supported by a smartphone application, via easy wireless Bluetooth connectivity and a platform for remote monitoring. The proposed device computes the mass flow by measuring the differential pressure in a venturi tube using a factory calibrated and temperature compensated differential pressure sensor. The latter is directly connected via a two-wire digital interface to the main control electronic board, and the obtained data are linearized. The venturi tube was preferred over a laminar flow restrictor, due to its simplicity and smooth easy to swipe surfaces despite its higher non-linear response characteristics. It is detachable from the whole device allowing easy disinfection or replacement, thus providing enhanced infection protection. The blood oxygenation and pulse rate are measured by an extremely sensitive and stable factory calibrated module, which includes internal LEDs, photodetectors, optical elements, and low-noise electronics with ambient light rejection. The device is entirely controlled by the smartphone and has no moving mechanical parts, displays, or buttons, thus offering high reliability and low production cost. The preliminary results showed that the proposed design solution is robust, user friendly and can deliver accurate and consistent respiratory and oximetry test results at the point of care, without the need for calibration.