A new wearable sensor can determine muscle fatigue from sweat

07-01-2022 |   |  By Robin Mitchell

Recently, a new sensor has been developed that allows for the detection of muscle fatigue by observing the pH of sweat. How is exercise strain often overlooked, what does the new sensor do, and could it help prevent over-exercising?

How is exercise strain overlooked?

A problem that affects the majority of people on the planet is not getting enough exercise. The invention of automotive vehicles and automated systems combined with delivery services sees less need for individuals to move around. While this may be highly convenient, it is incredibly unhealthy for the human body. Such inactivity increases the risk of cardiovascular and weight-related diseases and even reduces the immune system’s effectiveness.

To try and encourage exercise, many wearable medical devices have been developed that allow for the tracking of heart rate, calorie burn, and the number of steps done. But a portion of society takes exercise too far, which can damage the human body. For example, excessive dieting can result in too much weight loss, making it harder for the body to repair the damage. The reduced nutrition intake can reduce the immune system’s effectiveness.

But there is also the possibility that muscular damage can occur from too much exercise. This is particularly difficult to foresee as pain resulting from muscular injury often takes time to show (well after an exercise session). Despite the many sensors that exist for determining an individual’s immediate health, none can determine if the damage is being done.

Researchers develop exercise strain wearable sensor

Recently, researchers from KAUST have developed a new wearable sensor that can determine muscular fatigue from sweat. The new device utilises nanomaterials called MXenes, which are similar to graphene in that they are 2D in structure. Like graphene, MXene nanomaterials are non-toxic and use elements such as titanium, nitrogen, and carbon, making them highly ideal for use in biosensors.

The new device can detect muscular fatigue by measuring the pH of sweat. Simply put, as muscles begin to fatigue, they produce excessive amounts of lactic acid, which can change the pH of the resulting sweat from the body.

The original sensor was designed to track muscular movement by embedding MXene materials in a hydrogel compound and measuring the electrical resistance. As muscles move, the sensors output changes and this change is highly consistent. However, the researchers noticed that the sensor was extremely sensitive to changes in pH level, and this change in sensor output can easily be detected.

Thus, the sensor can track both muscular movements and pH change, and both of these can be used to determine muscular fatigue. Currently, the researchers are working to improve the sensors long-term capabilities with the goal of creating a commercial device.

Could such a sensor help with exercise fatigue?

If the sensor developed by the research can detect muscular fatigue from pH alone, then it is very likely that future medical sensors will deploy such technology. Those who have injured themselves without knowing could use such devices to prevent further damage, and this would potentially allow for significantly reduced recovery times.

The sensor technology could also be useful for general medical diagnosis when determining the extent of muscular injuries without needing to use invasive procedures. This may also be useful for individuals who require physiotherapy and need to avoid overexerting themselves during rehabilitation.

Many sensors developed around biodata often try to look at heart rate, sweat, and breathing, but very few try to look for physical damage. Even if the sensor developed by the researchers doesn’t make its way into the commercial space, it could still pave the way for sensor development that specifically looks for ongoing damage.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.

Related articles