Acoustic Transmissions for Wireless Communications and Power Supply in Biomedical Devices

In this paper, we demonstrate the principle of acoustic transmission for communications and power supply, in-vivo. The acoustic transmissions are intended to be used for fixed implanted biomedical devices, such as pacemakers, but more importantly, neural implants were wired and wireless RF communications cannot be used. The acoustic transmissions can be used for both wireless communications and to recharge the device, in-vivo, using conventional piezoelectric power harvesting techniques. Current research in biomedical engineering is looking at implantable devices to regulate conditions such as Parkinson’s and other neuromuscular conditions. Transient devices, such as those used in the gastrointestinal track, make use of high frequency RF, were the permittivity of the human body begins to decrease. However, significant power is still required. This results in local tissue heating, due to the absorption of the EM radiation. This heating has side effects that limit the exposure times for safe practices. For neural implants, were the goal is to have the product implanted for long periods of time, without complications and minimal side effects, RF communications cannot currently be used. Acoustic transmissions represent an ideal low power method of communicating with in-vivo biomedical devices, and for recharging them through power harvesting. In this work, we present results showing the performance of the communications channel and sample communications signals, through a biological specimen. The frequency response, transfer function and transient response (at resonance) of the communications channel were measured. Due to the frequency response of the communications channel, PSK was chosen as the modulation method. Successful communication was achieved through the communications channel. We also show the result of preliminary work on harvesting the acoustic signals to provide power for recharging in-vivo Biomedical devices.