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Countering diabetes and other chronic diseases with micro-implants

Fraunhofer researchers want to use micro-implants to specifically stimulate nerve cells electrically and thus treat chronic ailments such as asthma, diabetes or Parkinson's. What makes this form of therapy so special and what challenges the researchers still have to solve.

According to a study by the Robert Koch Institute, every fourth woman is affected by urinary incontinence. This form of bladder weakness has so far been treated with pelvic floor training, special pacemakers, medication or even surgery. With the help of micro-implants, these sometimes lengthy and complex forms of therapy could be dispensed with. The highlight: the electrical stimulation helps certain areas of the body to perform their function when required.

Vasiliki Giagka, group leader at the Fraunhofer Institute for Reliability and Microintegration IZM, explains the method: "Electronic implants can trigger interrupted signals, they can block unwanted signals, but they can also bridge signals to other parts of the body. In patients who have the ability lost control of their bladder, a bioelectronic implant could measure bladder volume at any time and send a message when a person should go to the bathroom. In addition, it could stop accidental emptying of the bladder by high-frequency stimulation of the nerve concerned. "

To make this possible, Giagka's team is working with researchers from the TU Delft on miniaturized, flexible and, above all, durable electronics. On the one hand, such electronic systems must have a sensor unit that detects and processes the bubble volume. In addition, the data must be sent wirelessly from the body - a challenge, as the human inner workings with its organs and body fluids are extremely unfavorable for the transmission of radio signals. And another important function must be wireless: the loading of the implant by ultrasound. Ultrasonic waves set tiny vibrating bodies in the implant in motion and deform it. This elastic deformation is converted into electricity.

In addition, such microimplants can control nerve cells through electrodes and activate physiological processes through electrical impulses. These flexible electrodes are connected to microchips up to 10 micrometers thick. The aim is to create feedback loops between nerve cells and the micro-implants and thus to develop personalized and local therapies for the patients. In order to avoid the body's rejection reactions at the neural interfaces, the bioelectronics engineers working with Giagka use biocompatible materials such as polymers, precious metals and silicon for electronics.

For some time now, research has been using the term Elektrozeutika for such microimplants, because miniaturized electronics are used instead of pharmaceutical products: electricity instead of pills. With this approach, entire therapies could be developed from scratch and undesired side effects could be minimized. In addition to incontinence, several common chronic diseases are treatable. The prerequisite is that their mechanisms of action can be specifically influenced by electrical stimulation: Asthma, diabetes, Parkinson's, migraine, rheumatism, high blood pressure - the list is long and the research potential is enormous.

However, before the electroceuticals can be used on a larger scale, some hurdles still have to be overcome: "We cannot yet predict when the first clinical trials will be possible: We are currently developing suitable test models that will check the reliability of the implants throughout the entire process until then we will continue to miniaturize and optimize the stimulators ", says Vasso Giagka. The longevity of the microstimulators in particular has been a challenge so far. After all, the implants should function reliably in the body for several decades. The aim of miniaturization is to achieve an overall size of less than one cubic centimeter.

Giagka's team therefore pays particular attention to increasing the service life of the implants. To do this, they load the microsystems with electromagnetic oscillations, humidity and temperature in reliability tests and first calculate the actual service life from them.
In addition, they adapt the chip design in such a way that the electromagnetic loads are reduced during operation. This significantly extends the service life of the implants and the possible duration of their measurement capability. The team is aiming for a total service life of decades.

Vasiliki Giagka, who has set up a working group on "Bioelectronics Technologies" at Fraunhofer IZM as part of the "Fraunhofer Attract" funding program and holds an assistant professorship at the TU Delft, has networked with partners throughout Europe, the USA and in Asia Implement electrical stimulation therapies through micro-implants into medical practice. For another aspect that will have a major impact on the acceptance of microimplants - data security - it is cooperating with the Fraunhofer Center for Digital Networking.

last edited: 02/26/2020