Biocoin Platform

Biocoin is a modular wearable electrochemical sensing platform that integrates custom electronics, embedded firmware, and host-side software for multi-analyte detection in biofluids such as sweat and interstitial fluid.

Developed by the BioEE Group at the University of California, San Diego, Biocoin combines multimodal biosignal acquisition with wireless communication, microfluidic interfacing, and open analytical tools.

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Repository Overview

This repository contains the design assets for the Biocoin platform across hardware, firmware, software, and mechanical fixtures.

Folder	Description
firmware/	PlatformIO-based firmware for the nRF52840 controller and AD5940 analog front-end, including BLE control and data streaming.
software/	Python host software for BLE communication, technique execution, logging, and result export.
PCB/	PCB schematics, layouts, Gerbers, assembly files, and shared component libraries.
fixtures/	Mechanical design assets, fabrication exports, and fixture models for assembly and validation.

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Architecture

The Biocoin system is organized as:

Host software (Python CLI/package in software/)
  -> BLE GATT protocol
  -> nRF52840 firmware (firmware/)
     - SensorManager and technique implementations
     - AD5940 driver and board support
     - BLE, power, battery, and storage modules
  -> AD5940 analog front-end
  -> Electrochemical cell and integrated sensors

The current firmware structure is consistent with a FreeRTOS-based design using SensorManager, technique-specific sensor modules, and BLE streaming tasks.

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Supported Techniques

Technique	Description	Output
CA	Chronoamperometry	Current vs. time
CV	Cyclic Voltammetry	Current vs. voltage
DPV	Differential Pulse Voltammetry	Peak current vs. potential
SWV	Square-Wave Voltammetry	Differential current vs. potential
IMP / EIS	Impedance spectroscopy	Magnitude and phase
OCP	Open-circuit potential	WE potential vs. RE
TEMP	Temperature monitoring	Voltage-derived temperature data
IONTOPH	Iontophoretic stimulation	Current control and monitoring

Each technique can be configured from the host and controlled over BLE. Data-producing techniques stream results back to the host software.

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Development Requirements

Firmware

• PlatformIO for build and flash workflows
• A supported nRF52840 board configuration for the Biocoin hardware
• Optional DFU tooling such as Nordic nrfutil

Software

• Python 3.13 or newer
• Recommended: uv for environment and dependency management
• Python dependencies defined in software/pyproject.toml:
  • bleak
  • colorama
  • numpy

Hardware and Mechanical

• Altium Designer or another tool capable of reviewing the PCB source/export files
• CAD software such as SolidWorks or FreeCAD for fixture review and export

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Typical Workflow

1. Build and flash the firmware in firmware/.
2. Use the Python tooling in software/ to connect over BLE.
3. Run a supported electrochemical technique and collect results.
4. Review or update board and fixture assets in PCB/ and fixtures/.

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Example Directory Layout

Biocoin/
|-- firmware/   # Embedded firmware, docs, scripts, and tests
|-- software/   # Python package, CLI runners, tests, logs, and results
|-- PCB/        # Board designs, Gerbers, assembly outputs, libraries
`-- fixtures/   # Mechanical assets and fabrication files

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Licensing

This repository contains both software and hardware design assets. Unless otherwise noted:

• firmware/ and software/ are provided under the MIT License.
• PCB/ and fixtures/ are provided under the CERN-OHL-W v2.0 license.

See the top-level LICENSE file for the repository-level license notice.

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Authors and Maintainers

BioEE Group, University of California, San Diego

Principal Investigator: Prof. Drew A. Hall

Contributors:

• Risab Sankar
• Tyler Hack
• Members of the BioEE Group (UCSD ECE)