ABSTRACT
In this paper, we present hardware-software methodology to measure and calculate heart and respiratory rates by using single, low-cost microcontroller chip of limited computation and memory performances, as ATTINY85. Sensors and analog front-end are very simple, directly interfaced to microcontroller pins. Implemented time and frequency domain signal processing algorithms are optimized for low-bits, low-memory architectures and allow fast reading of rates, provide satisfactory accuracy, noise immunity and low power consumption. The same methodology can be used in similar applications to determine dominant spectral frequency of slow signal, from a smaller number of points. © 2022 IEEE.
ABSTRACT
A low cost, simplified hardware and software interface capable of measuring and analyzing photoplethysmogram signal is presented in this paper. Two most important vital signs, oxygen saturation and heart rate are extracted, while the same principle can be extended to other parameters associated to this signal. Overall system consists of specially designed analog front-end, based on the off-the-shell components and microprocessor of modest processor and memory capabilities, like Arduino series. In addition to hardware simplification, the optimized software algorithms for signal acquisition, process handling, on-chip signal processing, feature extraction and basic communication are demonstrated. Satisfactory and repeatable results are obtained with accessibility to raw signal. Developed interface is a low-cost alternative to expensive OEM solutions, especially suitable for its integration in wearables, telemedicine and IoT healthcare systems in process of COVID-19 diagnosis and treatment. The design challenges, starting idea, system architecture, implementation details and preliminary testing results are shortly elaborated. © 2021 IEEE.