Abstract
An approach to improve wireless power transfer (WPT) to implantable medical devices using loop antennas is presented. The antenna exhibits strong magnetic field and dense flux line distribution along two orthogonal axes by insetting the port inside the antenna area. This design shows excellent performance against misalignment in the y-direction and higher WPT as compared with a traditional square loop antenna. Two antennas were optimized based on this approach, one wearable and the other implantable. Both antennas work at both the ISM (Industrial, Scientific, and Medical) band of 433 MHz for WPT and the MedRadio (Medical Device Radiocommunications Service) band of 401–406 MHz for communications. To test the WPT for implantable medical devices, a miniaturized rectifier with a size of 10 mm × 5 mm was designed to integrate with the antenna to form an implantable rectenna. The power delivered to a load of 4.7 kΩ can be up to 1150 μW when 230 mW power is transmitted which is still under the safety limit. This design can be used to directly power a pacemaker, a nerve stimulation device, or a glucose measurement system which requires 70 μW, 100 μW, and 48 μW DC power, respectively.
Highlights
Wireless power transfer (WPT) to implantable devices has attracted significant attention in the last decade. It is a promising choice for delivering power to the implants which may avoid the surgery required to replace batteries [1]. is power transfer takes place when a voltage is induced at a receiver due to electric and magnetic fields generated by an external transmitter [2]
Antennas can be used in power transmission based on this technique if it is placed in close proximity within the near-field region. ese antennas are wearable on the body and used to wirelessly charge as well as communicate with implants
It has an RF to DC conversion efficiencies of 28% at −10 dBm input power up to more than 70% at 10 dBm input power. is rectifier can offer more than 50% efficiency when the input power is larger than −4 dBm. e main reason for the difference in efficiency is because the impedance of the diode changes with the input power level, and the efficiency of the rectifier is a function of the input power. e circuit was fabricated on a Duroid 5880 substrate with a relative dielectric constant of 2.2 and a thickness of 1.57 mm
Summary
Muayad Kod ,1 Jiafeng Zhou ,2 Yi Huang ,2 Muaad Hussein ,3 Abed P. An approach to improve wireless power transfer (WPT) to implantable medical devices using loop antennas is presented. Two antennas were optimized based on this approach, one wearable and the other implantable. Both antennas work at both the ISM (Industrial, Scientific, and Medical) band of 433 MHz for WPT and the MedRadio (Medical Device Radiocommunications Service) band of 401–406 MHz for communications. To test the WPT for implantable medical devices, a miniaturized rectifier with a size of 10 mm × 5 mm was designed to integrate with the antenna to form an implantable rectenna. Is design can be used to directly power a pacemaker, a nerve stimulation device, or a glucose measurement system which requires 70 μW, 100 μW, and 48 μW DC power, respectively To test the WPT for implantable medical devices, a miniaturized rectifier with a size of 10 mm × 5 mm was designed to integrate with the antenna to form an implantable rectenna. e power delivered to a load of 4.7 kΩ can be up to 1150 μW when 230 mW power is transmitted which is still under the safety limit. is design can be used to directly power a pacemaker, a nerve stimulation device, or a glucose measurement system which requires 70 μW, 100 μW, and 48 μW DC power, respectively
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