Researchers at Purdue University's Birck Nanotechnology Center have tested a dime-size prototype to prove the concept and expect to have the miniature version completed by the end of summer, said Babak Ziaie, associate professor in the School of Electrical and Computer Engineering. "Currently, there is no way of knowing the exact dose of radiation received by a tumour," Ziaie said. "Because most organs shift inside the body depending on whether a patient is sitting or lying down, for example, the tumour also shifts." Doctors could use the wireless technology to precisely track a tumour by using three or six coils placed around the body to pinpoint the location of the electronic device. The passive wireless transponder, has no batteries and will be activated with electrical coils placed next to the body. "It will be like a capsule placed into the tumour with a needle," said Ziaie.
Researchers tested the prototype with the radioactive material cesium. The device, which contains a miniature version of dosimeters worn by people in occupations involving radioactivity, could provide up-to-date information about the cumulative dose a tumour is receiving over time.
The technology uses the same principle as electret microphones. They contain a membrane that vibrates in response to sound waves. Between the membrane and a metal plate is an air gap that serves as a capacitor. As the membrane vibrates, the size of the air gap changes slightly, increasing and decreasing the capacitance and altering the flow of electric current through the circuit, creating a signal that transmits information stored in the dosimeter. "It's basically like a very small tuning circuit in your radio," Ziaie said. "This will be a radiation dosimeter plus a tracking device in the same capsule. It will be hermetically sealed so that it will not have to be removed from the body."
MEDICA.de; Source: Purdue University