# Digital glucose meter prototype on Arduino

> An Arduino firmware that reads the current of a glucose test strip through an INA219 sensor on I²C, detects the strip and the reaction peak, and converts the reading to mg/dL on a 20×4 LCD — a study prototype, with its mechanical parts designed in CAD.

- URL: https://mojtabaamini.com/projects/glucose-meter-en
- Language: en
- Author: Mojtaba Amini, AI Software Engineer (Verona, Italy)
- Details: 2020 · Personal project

- **Role**: Embedded developer — firmware, electronics integration, mechanical parts
- **Period**: 2020
- **Context**: Arduino · I²C · open source
- **Technology**: Arduino · C++ · INA219 · I²C · LCD · CAD

## Hardware

An Arduino board, an INA219 current and voltage sensor on the I²C bus, set to its 16 V / 400 mA calibration for more resolution on small currents, a 20×4 LCD on I²C, and mechanical parts designed in CAD (STEP files in the repository).

## Firmware

A state machine: detect the strip from a low but non-zero shunt voltage, ask for blood on the display, wait for the reaction, find the current peak, measure about 4.5 seconds later with millis() timing, convert with a linear calibration to mg/dL and show the result.

## What it teaches

Calibration is the real product: temperature, strip batch and reaction time change the reading, and a real device needs clinical validation and certification under the EU IVDR. This was a study prototype, not a medical instrument.

## Further reading

- [A glucose meter on Arduino: what an embedded prototype teaches](https://mojtabaamini.com/writing/arduino-glucose-meter-en) (Article · Sep 2026): In 2020 I built a digital glucose meter prototype with an Arduino, an INA219 current sensor and an LCD. How it works, where the code was fragile, and why a prototype is not a medical device.

Related service

- [Embedded systems, IoT and data acquisition](https://mojtabaamini.com/services/embedded-iot): C/C++ firmware, sensors, CAN bus and telemetry, up to AI models on the collected data.

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