A research team from the MIT Media Lab has developed an injectable antenna, only the size of a sand grain, that can provide wireless power for medical devices implanted in deep tissues of the human body, such as pacemakers for heart disease patients and neural regulators for epilepsy or Parkinson's disease patients. The relevant research results were published in the October issue of the IEEE Journal of Antennas and Propagation. The team stated that this miniature antenna does not require batteries and can be implanted into the body through a needle, thus avoiding major surgical procedures. It is an important breakthrough in achieving miniaturization of deep tissue implantation devices. At present, deep tissue implant devices usually rely on two power supply methods: one is to implant batteries several centimeters long through surgery, which need to be replaced regularly; The second is to implant centimeter level electromagnetic coils to obtain electrical energy wirelessly. However, the coil power supply method can only work effectively under high-frequency conditions, which can cause tissue heating and limit the safe power supply capability of the device at the sub millimeter scale. The team stated that once the size exceeds the limit, these devices may damage human cells. Therefore, developing antennas with a size less than 500 microns that can operate efficiently at low frequencies has become a technical challenge. This time, the team has developed a new antenna that is only 200 microns in size and can operate at a low frequency of 109 kHz. The core technology lies in the use of a composite structure of magnetostrictive thin film and piezoelectric thin film: when an external magnetic field is applied, the magnetostrictive film undergoes deformation, and the piezoelectric film converts this deformation into an electric charge. The test results show that compared with the same sized implanted antenna that relies on metal coils and operates in the gigahertz frequency band, the output power of the new antenna has increased by 4-5 orders of magnitude. Team introduction: The magnetic field required to activate the antenna is provided by a device similar to a wireless phone charger, which is compact in size and can be used as a skin patch or placed in a shallow pocket. Moreover, due to the fact that the antenna is manufactured using the same process as the microchip, it is easy to integrate with existing microelectronic systems. In addition, the manufacturing process of this antenna is easy to scale up and can simultaneously inject multiple antennas and implants to treat a large range of lesions. In addition to pacemakers and neuromodulators, this antenna can also be applied in fields such as glucose sensing in vivo. The existing optical glucose sensing circuit is relatively mature, and combined with this wireless power supply technology, it will greatly promote its non-invasive integration and application in vivo. (New Society)