Pressure Switch Inside Head -- COMPAMED Trade Fair

Pressure Switch Inside Head

Photo: Pressure sensor

To this day it remains a mystery why the cerebral pressure in certain people suddenly increases. The consequences, however, are better understood: The blood circulation is disrupted and after a while parts of the brain may die off, similar to what occurs in a stroke. This is how dementia takes its insidious path. Experts estimate that up to ten percent of all cases of dementia in Europe can be attributed to rising blood pressure in the brain. Still, making the diagnosis is tough. People with a heightened susceptibility to a rise in intracranial pressure must be treated with intensive medical care today. A probe is inserted that goes from the outside through the skullcap to the brain. The cable keeps the patient connected to the measuring apparatus. Since cerebral pressure fluctuates, it takes extensive measurements in order to reach a definitive diagnosis of this disease. Patients therefore have to stay in hospital typically for several days, and sometimes even weeks.

For some time now, medical device engineers have been working on an intracranial pressure probe that operates without a cable and can be read from the outside using radio wave transmission. But there is no established product on the market to this date for long-term implantation, because the sensors always have the same problem: Their casing – which previously had been produced primarily from biologically accepted synthetics – allows moisture to penetrate, which destroys the sensor in just a few days – or even hours.

Researchers at the Fraunhofer Institute for Biomedical Engineering IBMT in St. Ingbert have now developed a small sensor that really stays waterproof. They had to give up the idea of encasing a sensor with synthetic materials. Instead, they produced the casing from high-grade metal. From the outside, the probe resembles a thick button cell battery. It is only about one centimeter high, two centimeters wide and in the future, should get even smaller. Resting on its inside is a pressure sensor made of silicon, similar to those sensors used today in automobiles, to handle the demanding measurement tasks.

“The cover of the tiny metal container is made from a pliable metal membrane that reacts to pressure changes in the brain,” as project manager Doctor Thomas Velten describes the unique aspects of the system. This pressure is transmitted to the silicon chip on the inside. The measurement value is transmitted to the measuring device outside the body through a radio impulse. “The benefits are immense,” says Velten. “The patient no longer has to be checked in on an inpatient basis but comes to the clinic for a brief measurement appointment instead.”; Quelle: Fraunhofer Gesellschaft