Portable Electrochemical Analyzer
End-to-end development of an STM32F303-based electrochemical measurement platform spanning mixed-signal hardware, PCB design, real-time firmware, signal processing and PC software.
- Complete sensor-to-software measurement system: analog front end, PCB, embedded firmware and C# application
- STM32F303 with timer/DMA-driven DAC waveform generation and synchronized ADC acquisition
- Potentiostat, transimpedance amplifier, bipolar DAC conditioning and differential ADC signal chain
- Implemented EIS, CV and LSV measurement modes, with experimental SWV development
- Validated experimentally against PalmSens and laboratory impedance-analysis equipment
Project Overview
A compact electrochemical measurement platform developed as part of my M.Sc. in Embedded Systems at Technische Universität Chemnitz.
The goal was to build a low-cost instrument around a single STM32F303 ARM Cortex-M4 capable of generating electrochemical excitation signals, controlling a three-electrode cell, measuring its voltage and current response, processing the acquired data and presenting the results through a PC application.
The project covered the complete engineering chain:
Analog front end → PCB → embedded firmware → signal processing → communication → PC software → experimental validation
Read the detailed engineering article →
System
The STM32F303 forms the digital core. Its internal DACs generate the excitation waveform and DC offset/ramp, while synchronized ADC channels acquire cell-voltage and current feedback.
The custom analog front end provides three-electrode potentiostat control, transimpedance current measurement, bipolar conditioning of the MCU’s unipolar DAC outputs, differential ADC signal conditioning, selectable current ranges and buffered analog references.
A USART connection links the embedded system to a C# desktop application for configuration, visualization and data storage.
Hardware
I worked across the complete measurement signal chain, from excitation generation to ADC acquisition.
The hardware combines precision op-amp stages for DAC level shifting and summation, a potentiostat feedback loop, a transimpedance amplifier for microampere-range current measurement and differential ADC drivers.
The design required balancing analog gain, bandwidth, stability, noise and MCU converter limitations.
The circuitry progressed from simulation and breadboard development through schematic capture to a dedicated two-layer PCB. A separate power-supply board generated the analog and digital rails required by the mixed-signal system, including ±5 V, ±2.5 V, 3.3 V digital and 3.3 V analog supplies.
Firmware & Signal Processing
The firmware turns the STM32 peripherals into a synchronized waveform-generation and acquisition system.
Hardware timers and DMA coordinate DAC updates and ADC sampling rather than relying on software timing loops. This reduces CPU intervention and timing jitter while enabling deterministic acquisition.
For EIS, embedded processing calculates impedance information including magnitude, phase, real and imaginary components before transferring the results to the PC.
The implemented EIS excitation range extended from approximately 0.1 Hz to 100 kHz.
PC Software
I also developed the PC-side software in C#, covering serial communication, measurement configuration, parameter entry, test execution, visualization and result storage.
Measurement Capabilities
The common hardware/firmware platform was developed for:
- Electrochemical Impedance Spectroscopy (EIS)
- Cyclic Voltammetry (CV)
- Linear Sweep Voltammetry (LSV)
- Square Wave Voltammetry (SWV) — waveform generation and acquisition investigated experimentally; the complete processing path was not finalized within the project
Verification
The prototype was tested first with passive dummy cells and then with real electrochemical cells.
Measurements were compared against commercial reference equipment including PalmSens potentiostats and laboratory impedance-analysis equipment.
Validation included EIS Bode/Nyquist analysis and CV/LSV comparisons using electrochemical test solutions. The complete measurement chain was therefore evaluated rather than stopping at functional bench testing.
See the detailed measurements and engineering lessons →
Skills Demonstrated
Embedded systems: STM32F303, ARM Cortex-M4, Embedded C, timers, DMA, ADC, DAC, USART
Analog & measurement electronics: potentiostat design, transimpedance amplifiers, op-amp signal conditioning, differential ADC interfaces, voltage references, low-current measurement
Hardware development: simulation, schematic design, two-layer PCB layout, power-supply design, prototyping and bench debugging
Software: C#, serial communication, measurement configuration, visualization and data handling
Verification: oscilloscope debugging, dummy-cell characterization, electrochemical testing, Bode/Nyquist analysis and comparison with commercial instruments