Wireless midfield scheme for power transfer and bidirectional data transmission for capsule endoscopy

This paper presents a midfield scheme for wireless power transfer (WPT) and bidirectional data transmission for capsule endoscopy. Since the sub-gigahertz range has been considered as the optimal transfer solution for WPT into human body, sub-gigahertz frequency is chosen for both the power and data transfer. Midfield wireless power transfer and offset quadrature phase-shift keying (OQPSK) based bidirectional data transmission are detailed. Simulations show that a power transfer efficiency of up to 18% and gain bandwidth of 3.5MHz could be achieved with a 10mm by 20mm receiver at a distance of 8cm, with the delay time of 62.8ns, providing sufficient power and data rate for capsule endoscopy system.