To lead a healthy lifestyle it is essential to eat healthy and exercise regularly. People who exercise regularly would often reach a point during their workout session, where they feel extremely exhausted and could not carry on any further. Fatigue sets in when lactate (a form of Lactic acid) builds up in the muscles. Lactic acid is an end product of Glycolysis under anaerobic conditions. lactate starts to accumulate as a result of glucose metabolism in muscle cells. Lactate levels in the body build up to a level the muscles can no longer handle.
The level of Lactate in blood during exercise is used as an indicator for the athlete’s training status and fitness since elevated levels of blood lactate results in a decreased level of pH in blood finally results in fatigue.
Lactate has a significant importance in sports medicine, especially for determining physical fitness in athletes. Doctors and trainers monitor the lactate levels of an athlete to determine when he/she has reached the threshold of exertion, and also to detect if any metabolic or physiological disorder exists.
Traditionally it is done by testing blood lactate levels through finger pricks at regular intervals during training sessions, and sending the samples to the lab to test for lactate levels. This is very inconvenient for the athlete as it requires interrupting the training sessions every few minutes! But Dr. Joseph Wang and his team of researchers from our own prestigious University Of California San Diego – Department of Nanoengineering, have designed a wearable decal sensor that gauges the levels of lactate in sweat.
The temporary tattoo style wearable sensor is based on “Ion Selective Electrodes (ISE’s)- Non-Invasive potentiometric monitoring of epidermal pH levels”. The Solid contact polymer ISE’s are screen printed onto temporary transfer tattoo paper, the result is a tattoo based potentiometric sensor that has a rapid response to a wide range of pH changes. Like a tattoo the wearable sensor is pressed on to the skin and the backing paper is peeled off and behold the sensor kicks off to a start!
Components of the device: It consists of 3 electrodes, one electrode is made of silver and silver chloride inks, the other two are of conductive carbon inks. One of the carbon ink electrode is coated with Lactate Oxidase – and essential enzyme that catalyses the conversion of Lactate to Pyruvate and releases 2 electrons during the process.
When lactate in the sweat comes in contact with the electrodes, the two released electrons are transformed to current that is proportional to the amount of lactate in the blood. The current is measured by a cell phone sized small microampere meter connected to the electrodes in the sensor by wires.
This device is less invasive, non interrupting and a fast way of monitoring lactate levels.
The most recent breakthrough in the world of wearable biosensors is the project by a research team led by Oregon State University professor Gregory Herman. They have developed a contact lens that can detect the drop in blood sugar levels.
The prototype developed by the Oregon State University research team has a biosensor that includes Glucose Oxidase-an enzyme that breaks down glucose. When the enzyme in the sensor comes in contact with the glucose in tears, it oxidizes it. The oxidation causes change in pH triggering measurable changes in the electrical current. Tiny nanostructures were embedded within the biosensor, allowing the device to detect minute glucose concentrations found in tears.
This device is still in developmental stages and currently, the lab-tested prototype can only detect blood glucose levels, but in the future, the team believes it could detect other medical conditions – lactate (sepsis, liver disease), dopamine (glaucoma), urea (renal function), and proteins (cancers) too!
- Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring -Amay J. Bandodkar, Vinci W. S. Hung, Wenzhao Jia, Gabriela Valdés-Ramírez, Joshua R. Windmiller, Alexandra G. Martinez, Julian Ramírez, Garrett Chan, Kagan Kerman and Joseph Wang – Department of Nanoengineering, University of California San Diego, La Jolla, USA
A field effect glucose sensor with a nanostructured amorphous In–Ga–Zn–O network –