Biological impedance (BioZ) is an information-packed modality that allows for non-invasive monitoring of health and emotional state. Currently, most research involving tissue impedance is based on bulky or fixed-purpose hardware, which limits the scope of research and the possibilities of experiments. In this work, we present HEEPidermis: a System-on-Chip (SoC) which integrates all the blocks needed for tissue impedance measurement, including two 8-bit, arbitrary-signal current DACs, two VCO-based ADCs, and a RISC-V CPU to enable on-chip feature extraction for closed-loop operation. An event-based sub-sampler improves storage and energy efficiency for long-term recording. In addition to the versatile SoC, the digital back-end and behavioral models of the analog front-end are open-source, allowing fast system-level simulations or repurposing. The SoC was taped out on TSMC 65 nm LP process.
@article{arxiv.2509.04528,
title = {HEEPidermis: a versatile SoC for BioZ recording},
author = {Juan Sapriza and Beatrice Grassano and Alessio Naclerio and Filippo Quadri and Tommaso Terzano and David Mallasén and Davide Schiavone and Robin Leplae and Jérémie Moullet and Alexandre Levisse and Christoph Müller and Mariagrazia Graziano and Matías Miguez and David Atienza},
journal= {arXiv preprint arXiv:2509.04528},
year = {2025}
}