Wireless data transfer through biological tissues using near-infrared light: testing skull and skin phantoms

Light in the range of 700—1100 nm has many proven diagnostics and therapeutic medical applications. In this study, we demonstrate another potential application of light. We implemented a testbed to transmit data wirelessly through a human skull and biological phantoms mimicking skin tissues properties using near-infrared (NIR) light. Currently, radio frequency (RF) is widely used to transmit data wirelessly through biological tissues, example includes implants communications. However, RF communications contain interference and security challenges. In this study, we present a novel use of NIR light for wireless data transfer, for which a phantom is exposed to an externally modulated light source and the transmitted light through phantom is captured with a receiver. Initially, a high-resolution picture is successfully transmitted through skin phantom of 2 cm in depth. In the second phase, we successfully communicated through a human skull. Due to hardware limitations, we are able to achieve data rates in tens of kilobits per second. The minimum power applied to the phantoms measured during the data transmission from 810 nm light-emitting-diode (LED) is 0.098 W/cm². The measured optical power values are within the safe limit set by ANSI.Z136.1—2007 standard on laser safety, which is 2 W/cm² for 1 sec exposure of 830 nm wavelength. Initial results are encouraging and there are many possible applications for a system using light to transmit data wirelessly through biological tissues, including communication with brain implants and performing brain therapies.