Unlike drugs, active implants such as electroceuticals act locally, have fewer side effects and function directly through electrical signals, much like the body itself. Fraunhofer researchershave developed a new technology platform that can power active implants wirelessly via ultrasound. The experts are targeting widespread diseases such as high blood pressure, diabetes and Parkinson’s.
Scientists at the Fraunhofer Institute for Biomedical Engineering IBMT in Sulzbach developed a demonstrator that powers active implants wirelessly via ultrasound. The technology is a viable alternative to battery power and induction, as the device is smaller, requires no integrated batteries and is more efficient than inductive energy transfer.
Ultrasound waves are mechanical waves, emitted and absorbed by piezoelectric material in transmitters and receivers. The piezoelectric transducers change shape imperceptibly when a voltage is applied. This deformation releases mechanical waves, similar to sound waves from a loudspeaker, which then strike the piezoelectric receiver. The waves also cause the receiver to change shape, but with the difference that exactly the opposite reaction occurs: the deformation produces an electrical current.
Active implants are able to support certain bodily functions in people with illnesses, and to compensate for dysfunctions. Usually inserted just under the skin, they can control heart rhythm (pacemakers), support sensory perception (retinal and cochlear implants) and control artificial limbs (prosthetic hands). Measuring just a few centimeters, these small medical devices also handle some other major tasks, such as dosing drugs and supporting bone growth. “Our bodies work by means of electrical signals. Active implants model this functionality,” Schneider explains.
The basic structure of active implants has barely changed in recent years. Just like the first commercial pacemakers, they are composed of electronic components that are hermetically encapsulated in a titanium casing. Electrical feedthroughs in the titanium casing and cable connections conduct electrical impulses directly to electrodes in the cardiac muscle. The basic problem remains the power supply. Batteries have the disadvantage that they take up a lot of space – often half of the implant – and need to be changed regularly in a surgical procedure.