Biocompatible battery for medical implants is charged via ultrasound
Implantable medical devices such as hearing aids or pacemakers are of huge value, but keeping them charged up can involve clunky external power sources or repeated invasive surgeries to replace depleted batteries. Scientists in Saudi Arabia are putting forward a potential solution to this problem, developing a tiny implantable device that can be recharged through the skin with ultrasound instead.
How to keep medical implants running while inside the body is a problem for which we have seen some exciting potential solutions over the years. Possibilities include an MIT system that powers them with radio waves, a Stanford system that uses other types of electromagnetic waves, and pacemakers that use the body’s fluids as fuel.
The latest breakthrough in this area comes from scientists at King Abdullah University of Science and Technology (KAUST). Their system is based on a new type of biocompatible hydrogel that contains lots of water, allowing it to safely stretch and flex with the body, and also to conduct electricity.
This lattermost attribute is the result of new recipe whereby the team mixed polyvinyl alcohol with tiny pieces of MXene, which is a two-dimensional sheet of transition metal carbides, nitrides or carbonitrides. We have seen MXene used in the development of other promising technologies including sprayable antennas, artificial muscles for robots and next-gen battery components.
The team found mixing MXene into their hydrogel to form what they call "M-Gel" led to a material that could generate an electrical current when subjected to pressure, which forces electrical ions to flow through the water inside.
“Just as dissolving salt in water makes it conductive, we used MXene nanoflakes to create the hydrogel,” says Kanghyuck Lee, lead author of the study. “We were surprised to find that the resulting material can generate electric power under the influence of ultrasound waves.”
When this pressure is created via ultrasound it is an effect known as streaming vibration potential, and the team observed its effectiveness through a range of experiments. This involved planting the device several centimeters deep in a chunk of beef and using a variety of ultrasound devices, such as tips and probes used in research labs and hospitals, to quickly charge the device.
“This is another example of the impressive potential of MXene hydrogels we’ve been developing in our laboratory for sensing and energy applications,” says Husam Alshareef, a material scientist at KAUST.
The research was published in the journal ACS Nano.