Paperdoi:10.3390/technologies14100620
Relative Contact Load and PPG Modulation in a Low-LED-Drive Reflective Platform: A Single-Participant Feasibility Study
Technologies (MDPI), 14(10):620
TL;DR
Engineering feasibility study of sensor–skin contact load vs reflective PPG. Hardware: MAX30101 + nRF52833 + adjacent force-sensitive resistor (FSR); synchronized relative-load voltage and Red/IR PPG; one participant; five trials with fixed low→medium→firm→medium-return sequence. Mean FSR voltages ~500 / 1180 / 1997 mV across ascending stages.
- Form factor: other
Abstract
Reflective photoplethysmography (PPG) is sensitive to sensor–skin contact conditions. This engineering feasibility study examined synchronized relative-load voltage and Red/IR PPG in one participant using a MAX30101 sensor, nRF52833 microcontroller, and adjacent force-sensitive resistor (FSR). Five repeated trials followed a fixed low–medium–firm–medium-return sequence. Mean FSR voltages were 500.0 ± 22.1, 1179.8 ± 87.6, and 1996.6 ± 71.3 mV for the ascending stages. The 15 trial-stage summaries were repeated observations from the same participant. Higher FSR voltage was associated with lower IR AC/DC (within-trial r = −0.886; descriptive trial-fixed-effect slope, −0.0223 percentage points per 100 mV). Mean IR AC/DC was 0.560 ± 0.152% at low load, 0.218 ± 0.011% at firm load, and 0.381 ± 0.099% during medium return, compared with 0.330 ± 0.074% at the initial medium stage. Preliminary artifact controls documented setup-specific waveform changes. The adjacent FSR provides an uncalibrated spatial proxy rather than optical-site force or pressure. Fixed loading order prevents separation of load from time, adaptation, and loading history. These observations establish acquisition feasibility in the tested participant and arrangement, without establishing a causal pressure–response relationship, externally validated quality thresholds, or performance across users and devices.
Verbatim from the publisher's DOI record (opens in a new tab) · Publisher licence: https://creativecommons.org/licenses/by/4.0/
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Tasks & signals
Signals
Keywords
How it works
- Wavelengths
- red, IR
Cite this paper
APA
Shang, Y., Huang, Y., & Li, Z. (2026). Relative Contact Load and PPG Modulation in a Low-LED-Drive Reflective Platform: A Single-Participant Feasibility Study. Technologies. https://doi.org/10.3390/technologies14100620
BibTeX
@article{shang2026relative,
title = {{Relative Contact Load and PPG Modulation in a Low-LED-Drive Reflective Platform: A Single-Participant Feasibility Study}},
author = {Shang, Yang and Huang, Yucheng and Li, Ziang},
year = {2026},
journal = {Technologies},
doi = {10.3390/technologies14100620}
}Built from the hub record. Check it against the publisher before submitting.
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