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June 23, 2024

Magnets improve wireless devices

By Catie Paul | April 27, 2012

The application of magnets to generate electricity may soon provide patients who need surgically-implanted electronic devices with better-working options. Researchers led by Holger Lausch at the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS) in Hermsdorf, Germany, have designed and patented a wireless system to transmit power from a transmitter to a generator.
The scientists have built a transfer module that can provide a current of over 100 milliwatts. The module is small enough that it can be attached to the user's belt. In fact, since it has a range of 50 centimeters, it can be placed anywhere on the body.
The device works via a technique called magnetic coupling. In the transfer module, there is a magnet that rotates by means of a small motor. This magnet generates a magnetic rotary field, which is an area around a magnet that exerts a constantly changing force on another magnet.
In the receiver, there is another magnetic device which connects to this exterior magnetic field and starts rotating as a result. This rotation is converted into power. The magnetic field can pass through non-magnetic materials, such as bones, organs, water, plastic and a variety of metals, so there isn't any interference from them. Moreover, there are no harmful side effects to humans.
The transfer module can provide power to a variety of different applications, most of which are in the medical field. For instance, it can work with a variety of microelectronic implants. Some specific applications include providing power to pacemakers and infusion pumps. A pacemaker is a device inserted into the heart to regulate an erratic heartbeat. Infusion pumps that have been surgically implanted in a patient release a measured amount of a drug into a patient's body over time.
Another application the researchers have suggested for their system is providing power to ingestible endoscopic capsules which travel through a patient's gastrointestinal tract and take pictures. If a generator is placed inside the capsule, then doctors can assign a specific intestinal region to each picture taken.
All of these devices consist of various electronic units that require a power supply. Currently, they are powered by radio wave-based and inductive systems. Batteries aren't feasible because of their short lifespan.
Inductive charging requires having a system generate an electromagnetic field, which sends energy to an electrical device. Radio wave-based systems use radio waves, which are a form of particles that carry energy, to transmit power from one source to another.
These systems are not ideal, however, because their efficiency changes based on the location, position and movement of the person. Also, the range at which they can function is very limited. The new system is different from current models because the power is generated in the receiver module instead of having to receive power from another source.
This technology can be useful for larger applications as well, because it can easily be scaled up in size, range and performance capacity. Researchers believe that it can also be used in mechanical engineering and the construction industry.
For example, the transfer modules can provide power to sensors that have an airtight seal, such as those inside walls or bridges. Also, they can be used to support charge units that store power or activate different electronics.
Lausch and his team will be demonstrating this new technology's capabilities at the Hannover Messe from April 23 to April 27. As the testing device, they will use a hip implant that uses electricity to stimulate the joint and stimulate growth of cartilage and bone cells.

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