Wireless RF communication in biomedical applications

Abstract

This paper focuses on wireless transcutaneous RF communication in biomedical applications. It discusses current technology, restrictions and applications and also illustrates possible future developments. It focuses on the application in biotelemetry where the system consists of a transmitter and a receiver with a transmission link in between. The transmitted information can either be a biopotential or a nonelectric value like arterial pressure, respiration, body temperature or pH value. In this paper the use of radio-frequency (RF) communication and identification for those applications is described. Basically, radio-frequency identification or RFID is a technology that is analogous to the working principle of magnetic barcode systems. Unlike magnetic barcodes, passive RFID can be used in extreme climatic conditions-also the tags do not need to be within close proximity of the reader. Our proposed solution is to exploit an exciting new development in making circuits on polymers without the need for battery power. This solution exploits the principle of a surface acoustic wave (SAW) device on a polymer substrate. The SAW device is a set of interdigitated conducting fingers on the polymer substrate. If an appropriate RF signal is sent to the device, the fingers act as microantennas that pick up the signal, and this energy is then converted into acoustic waves that travel across the surface of the polymer substrate. Being a flexible polymer, the acoustic waves cause stresses that can either contract or stretch the material. In our case we mainly focus on an RF controllable microvalve that could ultimately be used for fertility control.

Surface Acoustic Wave Based Wireless MEMS Actuators for Biomedical Applications

“…SAW devices are widely used in MEMS applications, which require secure, wireless, and passive interrogation Jones et al (2008). These devices are recognised for their versatility and efficiency in controlling and processing electrical signals.…”

“…They are based on propagation of acoustic waves in elastic solids and the coupling of these waves to electric charge signals via an input and an output Inter Digital Transducers (IDT) that are deposited on the piezoelectric substrate. As shown in Figure 1, a SAW device consisting of a solid substrate with input and output IDTs Jones et al (2008). An IDT is an array of narrow and parallel electrodes connected alternately to two bus bars made out of thin-film metal.…”

“…For example, one would expect horizontal shear SAW mode to be more useful than Rayleigh SAW mode. This is because when a SAW device is in vitro, Rayleigh SAW mode is rapidly damped out, due to the pressure generated by the surrounding fluid (Jones et al, 2008). In contrast to the general approach of using the SAW device surface to transfer the fluid, the proposed approach uses an actuator (conductive plate), which is on top of the SAW substrate.…”

Design and characterisation of micro-diaphragm for low power drug delivery applications

“…Basically, we may think of a SAW device as consisting of a solid substrate with input and output IDTs. 5 As depicted in Figure 1, two microdiaphragms are electrostatically actuated using two SAW devices.…”

Design of a nanoswitch in 130 nm CMOS technology for 2.4 GHz wireless terminals

“…The increased popularity of 2.4 GHz ISM band devices for a different end user and corporate applications such as RFID, Bluetooth, Zigbee and Wi-Fi devices, non-contacting medical instruments, sensors etc., in the recent years, has raised the demand for small power and less off-chip components which tends to achieve integration of multiple transmitter/receiver chains on the same die [1][2][3]. As a result, highly integrated and area efficient designs are the current trends of IC design.…”