If sensor systems are able to efficiently abstract operational power from weak environmental energies, it could pave the way for the development of self-powered health diagnostic devices, among other things.
Now, a research team from Purdue University (PU) in Indiana has developed self-powered wearable triboelectric nanogenerators (TENGs) with polyvinyl alcohol (PVA)-based contact layers to monitor the user’s cardiovascular health. According to Wenzhou Wu, the research team’s leader, PVA-based TENGs show great potential for self-powered biomedical devices and could pave the way for new technologies that use biocompatible materials for the production of functional devices in energy, electronic, and sensor applications.
A close-up of Purdue University’s wearable triboelectric generator technology. It is applied to the user’s skin. Image Credit: Purdue University.
TENGs can transform environmental mechanical energy (that would otherwise be wasted) into electrical power, and recent advances in the technology have lent a significant boost to output performance. However, significant obstacles still exist that are hindering the further development of efficient TENGs, namely those based on biocompatible materials.
PVA, as one of the most widely used polymers in current biomedical applications, is believed by the PU team to present an opportunity for biocompatible wearables when used in TENGs.
In the study, the Purdue researchers demonstrate triboelectric devices built with PVA-gelatine composite films that exhibit stable and robust triboelectricity outputs. These wearable devices are able to detect the human pulse and capture the underlying cardiovascular information created by the pulse signals.
According to the researchers, their new understanding of the technology and the capabilities that it has presented could enable the design of novel materials for the next generation of biocompatible triboelectric devices. These could be used to monitor a range of physiological signals in health diagnostic applications.
Self-powered wearable triboelectric generators with PVA-based contact layers can be used to monitor cardiovascular health. Pictured: a close-up of Purdue University’s wearable sensor technology along with the medical readouts (heart rate graphs) that it can inform. Image Credit: Wenzhou Wu, Purdue University.
A Valuable Opportunity for Medical Devices?
Today, cardiovascular health is typically measured using echocardiograms. These detect electrical activity in the patient’s heart by using a range of sensor stickers and wires connected to an external machine. Echocardiograms are relatively invasive diagnostics tools that have not yet been adapted into wearable technology.
In contrast, wearable TENGs with PVA contact layers can, according to Wu, “produce fast readout with distinct peaks for blood ejection, blood reflection in the lower body, and blood rejection from the closed aortic valve, which may enable detection of common cardiovascular diseases, such as cardiovascular disease, coronary artery disease, and ischemic heart disease.”
Wu added that PVA could potentially be used in other future self-powered wearables, because the PVA-based triboelectric devices, which function as self-powered sensors to detect and monitor mechanical activities, can harvest the human body’s mechanical energy and use it to support the operations of other biomedical wearables.