HEEPidermis: a versatile SoC for BioZ recording

Biological impedance (BioZ) is an informationpacked 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 subsampler 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.

@misc{sapriza2025HEEPidermis,
    title = {{{HEEPidermis}}: A Versatile {{SoC}} for {{BioZ}} Recording},
    shorttitle = {{{HEEPidermis}}},
    author = {Sapriza, Juan and Grassano, Beatrice and Naclerio, Alessio and Quadri, Filippo and Terzano, Tommaso and Mallas{\'e}n, David and Schiavone, Davide and Leplae, Robin and Moullet, J{\'e}r{\'e}mie and Levisse, Alexandre and M{\"u}ller, Christoph and Graziano, Mariagrazia and Miguez, Mat{\'i}as and Atienza, David},
    year = 2025,
    month = nov,
    number = {arXiv:2509.04528},
    eprint = {2509.04528},
    primaryclass = {physics},
    publisher = {arXiv},
    doi = {10.48550/arXiv.2509.04528},
    urldate = {2025-11-07},
    archiveprefix = {arXiv}
}