SmartSweat - Lactate Sweat Analyte Band

Summary

According to an article by the American Chemical Society:

"Sports physiology will likely benefit from a technology able to account for high-resolution temporal lactate changes according to the intensity of the physical activity, rather than discrete information from centralized lab-based analysis.”

Lactate is a byproduct of muscular metabolism and an indicator of workout intensity. This market gap exists due to the difficulty in isolating and measuring specific chemicals in sweat, such as lactate. Currently, lactate sensors on the market are usually invasive and require lab analysis. This leaves a large market gap for non-invasive, real time lactate sensors, among athletes as well as the average consumer.

SmartSweat proposes an electrochemical lactate sensor working in combination with a mobile app to provide real-time lactate analysis on the user's sweat.

Technical Approach/Methodology

The SmartSweat system integrates biochemical sensing, wearable hardware, and embedded electronics into a single device.

At the core of the device is an enzyme-based lactate sensor, where lactate oxidase reacts with lactate in sweat to produce hydrogen peroxide. This reaction is detected electrochemically using a three-electrode system (working, reference, and counter), which is converted into a measurable current proportional to lactate concentration. The electrodes were manufactured using graphite and Ag/AgCl materials, and enzyme membranes were mixed then applied by drop-casting.

To measure the reaction, an Arduino-based potentiostat was designed to process this signal, maintaining a constant voltage and measuring the resulting current. The device is housed in a custom wearable armband, designed for comfort and consistent skin contact during physical activity, with a waist-mounted electronics pouch.

System verification included shunt resistor testing for circuit behavior, hydrogen peroxide testing for electrochemical detection, and enzyme-electrode testing to evaluate lactate sensing performance.

Outcomes

The SmartSweat project successfully produced a functional prototype of a wearable electrochemical sensing system, with successful validation of the electronics and detection mechanism.

A fully functional Arduino-based potentiostat was designed, maintaining a stable voltage and delivering current output data to be collected. This data was obtained through the successful detection of hydrogen peroxide, verifying the electrochemical sensing system. The custom wearable housing system was manufactured and assembled to be a portable, wearable device for validation.

Testing and validation results demonstrated a working prototype, showing a clear and repeatable relationship between hydrogen peroxide concentration and measured current.

However, full lactate detection was not achieved due to various limitations in the chemical subsystem. The lactate oxidase-based membrane did not produce hydrogen peroxide when exposed to lactate solutions. Potential issues included: enzyme degradation during shipping, inconsistency in membrane casting, limited access to labs/equipment, and time constraints for troubleshooting. Despite this limitation, validations were able to confirm that the electrical system is fully operational and the sensor can detect electrochemical reactions when present.

Overall, the SmartSweat prototype demonstrates the feasibility of a wearable electrochemical sensing device, while identifying the lactate enzyme layer as the primary system for future development.

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