Graphene Sensor Detects Lactic Acid in Sweat for Health Tracking

In collaboration with industrial partner Integrated Graphene, scientists at the University of Bath have developed a new chemosensor for lactic acid sensing, which operates with electricity but does not require electrodes or battery power. These findings are described in a study published in ACS Sensors.

The new design could be less expensive, have a longer shelf life, and be easier to miniaturize compared to enzyme-based sensors.

The sensor can detect lactic acid, a byproduct produced when the body uses glucose or carbohydrates as fuel (such as during exercise). Elevations in lactic acid have been associated with an increased risk of catastrophic organ failure and unconsciousness/coma.

This allows an easy-to-use sensor to be employed in remote settings, such as an athletics track, without requiring electricity-powered detecting equipment.

Lactic acid is commonly tested using an enzyme test, which has a short shelf life and requires battery-powered detecting equipment. The novel chemosensor monitors lactic acid using a chemical method and a graphene foam electrode surface.

Gii-Sens, the technology that powers the chemosensor and is referred to as ‘Graphene Foam’ in the study, is an electrode made of Integrated Graphene. Gii-Sens uses Gii™, a pure, porous 3D carbon nanostructure that is low-cost and eliminates the usage of unsustainable precious metals such as gold.

When lactate attaches to the sensor, it alters the carbon foam's electrical signal, also known as quantum capacitance. The foam detects low quantities of lactic acid without consuming it by analyzing variations in Gii’s electrical charge, allowing for level monitoring. Since it is a chemical sensor rather than an enzyme sensor, it has the potential to be less expensive, have a longer shelf life, and be more easily miniaturized.

Just as your contactless credit card doesn’t need an external power source to work because the proximity of the card reader is enough to power it, in a similar way, this sensor could create a small, measurable electrical current when lactate binds to it.

Frank Marken, Study Lead Author and Professor, University of Bath

Marken added, “This sensor, using Gii-Sens technology, addresses some of the main limitations with non-wireless current lactic acid enzyme tests. It will allow for a more simply operated sensor–opening up the potential for more regular, less invasive, and more reliable tracking of lactic acid, even during athlete performance.”

Lactic acid tests have several essential applications. Lactic acid is measured in professional sports to determine an athlete’s reaction to various intensities and training regimens. Athletes want to enhance their endurance and recovery by wirelessly tracking and improving their body’s ability to transfer and utilize lactate.

It is also utilized in medical settings to monitor cardiac diseases such as myocardial infarctions, atrial fibrillation, and atherosclerosis. This is helpful because increased lactic acid levels can impair the heart’s and blood vessels’ capacity to contract, affecting hemodynamics and normal function.

This development is another clear use case of Gii-Sens being integrated into sensing products and offering versatile applicability. The researcher’s test results using our Gii-Sens electrode opens up the possibility of more accessible and reliable health monitoring in remote environments, and we look forward to putting our highly sensitive Gii-Sens electrode at the heart of more groundbreaking innovations in the point-of-care diagnostics market.

Jean-Christophe Granier, Chief Executive Officer, Integrated Graphene

Journal Reference:

Wikeley, S. M., et al. (2024) Pyrene-Appended Boronic Acids on Graphene Foam Electrodes Provide Quantum Capacitance-Based Molecular Sensors for Lactate. American Chemical Society (ACS) Sensors.doi.org/10.1021/acssensors.4c00027.