Implantable Power & Communications
We designed an ultrasonic wireless energy transfer link to a visual cortical prosthesis implant device. Two ultrasonic transducers with 2 mm thickness and 12 mm diameter are implemented from scratch using Pz27 disc shape. The power transfer ultrasound link is demonstrated using 2 mm of tissue mimic in-vitro. The target voltage, required to operate the implant, of 1.8 V, 3.3 V, and 5 V is achieved. The ultrasonic link and the overall system efficiencies are found to be 14.99% and 25% respectively. This system is found to be working in 36% of the FDA limit (720 mW/cm2).
Acoustic power transfer has some advantages over other powering techniques such as:
Lower absorption in tissue
Shorter wavelength enabling smaller transducers
High power intensity threshold for save operation
Concept image for how the ultrasonic link can be used for powering the brain implant. Both of CMOS chip and the receiver transducer are fixed on the skull while the transmitter transducer transmits an ultrasonic signal through the skin.
Reference: Jaafar, B., Neasham, J., Chester, G. and Degenaar, P., 2017, October. Ultrasonic wireless powering link of visual cortical prosthesis implant. In Biomedical Circuits and Systems Conference (BioCAS), 2017 IEEE (pp. 1-4). IEEE.
Inductive Coupling Powering
We designed an power transmission system for visual prosthesis device which use the inductive coupling coil. This power transmission system could separately supply the static 3.3V and 5V voltage for implant micro controller and implant LED array. The system work could work as 90Khz or 13.56Mhz. The maximum working distance for inductive coupling coil is around 30mm and the wireless connection could across the skin tissue.
Concept image of inductive coupling powering system, the receiver supply the power for LED arrays and micro controller unit.
Ultrasound data communications
Our goal is to design an injectable implanted biomedical device that is capable of optical record and stimulating the biological tissue. Ultrasound link is employed for data communication, the implant communicates at 300 KHz radial resonances frequency. The wireless data transmission link is represented by two off-chip piezoelectric transducers with 300 KHz radial resonances frequency.
Concept image of how the implanted device can be used in virtual reality, the implanted injectable device is intended for optical stimulation and recording. The external transceiver receives the recorded data that travels through the tissue.
Bluetooth and Wi-Fi
We also build the data transmission system which based on Bluetooth and Wi-Fi technology for visual cortical prosthesis system, which could provide high speed and stable image data transmission for the system.