# CMOS-Compatible ZrO2‑Based Film for Photoplethysmography Sensors Enabling Accurate and Sensitive Health Monitoring

## TL;DR

A new self-powered PPG sensor using ZrO2-based film improves accuracy and sensitivity for health monitoring.

## Contribution

A CMOS-compatible, self-powered PPG sensor with enhanced responsivity and sensitivity is introduced.

## Key findings

- The sensor shows 26% higher responsivity and 23% improved sensitivity compared to conventional PPGs.
- It achieves high accuracy (<2% error) in estimating blood oxygen saturation (SpO2).

## Abstract

Photoplethysmography
(PPG) is a simple noninvasive technique for
the detection of multiple cardiovascular parameters, such as heart
rate, blood oxygen saturation (SpO2), systolic blood pressure,
and diastolic blood pressure. However, the current commercial PPG
technology is limited by several factors, including rigidity, bulkiness,
high cost, high power consumption of ∼10’s mW, poor
operational stability under ambient conditions, and susceptibility
to motion artifacts. In this work, we overcome many of these limitations
using a novel self-powered, miniaturized, low-cost, stable PPG sensor
based on a simple CMOS-compatible fluorite-type ferro/pyroelectric
Hf
x
Zr1–x
O2 thin-film photodetector device. Our novel self-powered
photodetector shows 26% higher responsivity and 23% improved sensitivity
(perfusion index of 3.7%) for sensing blood volume changes in microvascular
tissues compared to conventional PPGs, and a very high accuracy (<2% error) in the estimation of SpO2. The
simple sensor has strong prospects for replacing current PPG sensors
for health monitoring applications.