Medical Implants

Fraunhofer IMS is developing the next generation of intelligent closed-loop implants. They record the wearer's vital signs and, on this basis, can initiate therapeutic measures in a closed loop to improve the patient's health.

The trend towards continuous miniaturization of medical Implants is intended to open up new, previously unfeasible applications. In addition, an optimized overall performance is to be achieved for existing applications through increased functionality. These challenges are the elementary specifications for the development of highly complex implantable systems consisting of sensors, actuators, efficient electronics, sensor-related evaluation by AI algorithms, secure communication, long-term energy supply and biostable encapsulation.

Current developments feature ever higher integration densities, e.g. in order to establish the most efficient circuit technology possible up to sensor-based artificial intelligence. For this purpose, Fraunhofer IMS has established several highly integrated CMOS technologies from external foundries (with structure sizes between 65 and 180 nm) in its developments, which were selected according to their respective advantages. An important aspect, which was considered during the selection process, is that the costs of the used technology are in a suitable ratio to the quantities of implants to be produced, as planned by the customer. If required, the IMS bundles the development of several applications in order to provide the - from the microelectronics point of view - small quantities attractively. Previous developments of the IMS are characterized by a particularly efficient energy requirement of the circuit components. This is a necessary prerequisite for telemetric operation and also elementary for long implantation periods of more than 10 years.

Signal processing integrated close to the sensor enables advanced embedded AI data processing and efficient and securely encrypted communication to provide the user with the implant's medical data.

One focus of medical implant development is based on pressure sensors as the main sensory component. The Fraunhofer IMS has many years of expertise in the segment of pressure sensor implants and has its own microsystems technology manufacturing process for pressure sensors. In the current developments of the Fraunhofer IMS, the wafers with highly integrated semiconductor circuits are manufactured at an external foundry and the sensor elements are subsequently applied by means of surface micromachining. This post-CMOS approach allows the circuit technology to be specifically selected for the application in question. The result is monolithically integrated pressure sensors that have low power requirements and a small size despite high circuit performance.

In addition to pressure sensors, further processes have been developed in the microsystems technology clean room to enhance the functionality of medical implants. In the field of neural implants, e.g. electrodes for stimulating muscle or nerve cells can be applied directly to semiconductor components. They do not have to be contacted in a complicated way, but are directly connected to the electronics.

Medical implants must function stably in the body for many years, despite being exposed to the constant influence of moisture and biological defense reactions. Due to their limited geometric adaptability and wall thickness, the metal and ceramic encapsulants commonly used to date are an obstacle to opening up the smallest possible applications. For this reason, the Fraunhofer IMS develops nanoscale thin film encapsulations, which are realized by means of atomic layer deposition (ALD). These layers show extreme density and are conductive or insulating depending on the layer material (metal / ceramic). Biocompatibility has already been demonstrated for many materials. The current work on nerve stimulating implants is based on results on the retinal implant.

Medical implants must function stably in the body for many years, although they are exposed to the constant influence of moisture and biological defence reactions. Due to their limited geometric adaptability and wall thickness, the encapsulations made of metal and ceramics commonly used up to now are an obstacle to opening up the smallest possible applications. For this reason, the Fraunhofer IMS is developing nanoscale thin-film encapsulations, which are realized by means of atomic layer deposition (ALD). These layers show extreme impermeability and, depending on the layer material (metal / ceramic), are conductive or insulating. Biocompatibility has already been demonstrated for many materials.

The sensor systems of the Fraunhofer IMS are the basis for further developments towards theranostics – a neologism made up of therapy and diagnostics. In a few years, the sensors could not only record measured values and support the doctor in the diagnosis, but also independently adjust the pressure via the shunt system and thus actively control the patient's individual therapy.