A Dual-Band Differential Intraoral Antenna and System for Wireless Data and Radiative Near-Field Power Transfer

Abstract

Intraoral tongue drive system (iTDS) is a promising assistive technology for rehabilitating disabled persons. This article proposes a radiative near field power transfer (RNF-PT) system comprising an intraoral differential rectenna (rectifying antenna) and external power transmitter (RNF-Tx). A dual-band compact differential intraoral antenna operating in the Industrial, Scientific and Medical (ISM) band (2.45 GHz) and midfield band (1.9 GHz) is proposed for the data and power transmission modes, respectively. The proposed differential antenna and rectifier were designed and fabricated individually using a Rogers RT/duroid 6010 substrate. The differential rectifier shows a simulated conversion efficiency of 89.3% for a radio frequency (RF) input power of 14.78 dBm at 1.9 GHz with a 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> load. The maximum transmission coefficient of −25.95 and −24.93 dB was achieved at a separation of 22 mm for the closed and opened mouth conditions, respectively. The measured impedance bandwidths of the proposed antenna in both the closed and open mouth of the test subject are around 10% in the midfield band and around 9.5% in the ISM band, respectively. The measured peak gain in the minced pork and saline solution was −20.48 dBic, −18.25 dBic at the frequency of 1.9 GHz and −18.54 dBi, and −16.88 dBi at the frequency of 2.45 GHz, respectively. The specific absorption rate (SAR) values have also been analyzed through simulations for both data and power transmission modes and are found acceptable in the closed and open mouth placements. Based on these acceptable SAR values, the link margin was theoretically calculated where it could communicate over a reasonable distance. Thus, the proposed intraoral differential antenna with a rectifier is ideal for data and PT support in iTDS-based applications.