Low power wireless ultra-wide band transmission of bio-signals

The paper shows the design of microelectronic circuits composed of an oscillator, a modulator, a transmitter and an antenna. Prototype chips were recently fabricated and tested exploiting commercial 130 nm and 180 nm CMOS technologies. Detected signals have been measured using a commercial Ultra-Wide-Band amplifier connected to custom designed filters and a digital demodulator. Preliminary results are summarized along with some waveforms of the transmitted and received signals. A digital Synchronized On-Off Keying (S-OOK) was implemented to exploit the Ultra-Wide-Band transmission. In this way, each transmitted bit is coded with a S-OOK protocol. Wireless transmission capabilities of the system have been also evaluated within a one-meter distance. The chips fit a large variety of applications like spot radiation monitoring, punctual measurements of radiation in High-Energy Physics experiments or, since they have been characterized as low-power components, readout of the system for medical applications. These latter fields are those that we are investigating for in-vivo measurements on small animals. In more detail, if we refer to electromyographic, electrocardiographic or electroencephalographic sig- nals, we need to handle very small signal amplitudes, of the order of tens of mV, overwhelmed with a much higher (white) noise. In these cases the front-end of the readout circuit requires a so-called amplifier for instrumentation, here not described, to interface with metal-plate sensor’s outputs such those used for electrocardiograms, to normal range of amplitude signals of the order of 1 V. We are also studying these circuits, to be also designed on a microelectronic device, without adding further details since these components are technically well known in the literature. The main aim of this research is hence integrating all the described electronic components into a very small, low-powered, microelectronic circuit fully compatible with in-vivo applications.