A multimodal approach for sleep apnea detection: SpO<sub>2</sub> and force sensitive sensors in a flexible 3D-printed wearable.

Abstract

. The diagnosis of sleep apnea relies on the evaluation of polysomnography (PSG) recordings by experienced health monitoring practitioners. The labor-intensive nature of PSG and it's required complex instrumentation limit its widespread use across the general population. This research inquest offers a wearable health monitoring device in response to these challenges. The device incorporates a custom-fabricated force sensor resistor (FSR) seamlessly integrated with a microcontroller and pulse oximeter (SpO₂) within a 3D-printed enclosure. Real-time respiratory and oxygen saturation data are wirelessly transmitted to a web-based interface for comprehensive and automated sleep apnea diagnosis. This prototype provides a comfortable, easy-to-use solution capable of accurate and automated diagnosis of sleep apnea. The sensor is fabricated by spray-coated silver ink finger electrodes, which were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX), confirming the presence of high silver content (97.6%) and low oxygen (2.4%), ensuring good electrical conductivity. Additionally, the designed finger electrode was simulated by COMSOL Multiphysics simulations software through repeated trials, suggesting a consistent and direct relationship between applied pressure and voltage output as per the Ohm's law. The sensor's voltage output varied linearly, with force (N) from 0 to 5 V and force (N) from 0 to 40 Newton. The COMSOL simulations uses electrostatic and moving mesh models matched with real-world experimental results further validated the sensor. The minimal non-linearity observed in practical scenarios proves the robustness of the sensor.