Current wireless technologies, such as wireless body area networks and wireless personal area networks, provide promising applications in medical monitoring systems to measure specified physiological data and also provide location-based information, if required. With the increasing sophistication of wearable and implantable medical devices and their integration with wireless sensors, an ever-expanding range of therapeutic and diagnostic applications is being pursued by research and commercial organizations. This paper aims to provide a comprehensive review of recent developments in wireless sensor technology for monitoring behaviour related to human physiological responses. It presents background information on the use of wireless technology and sensors to develop a wireless physiological measurement system. A generic miniature platform and other available technologies for wireless sensors have been studied in terms of hardware and software structural requirements for a low-cost, low-power, non-invasive and unobtrusive system.

The emergence of wireless technologies and advancements in on-body sensor design can enable change in the conventional health-care system, replacing it with wearable health-care systems, centred on the individual. Wearable monitoring systems can provide continuous physiological data, as well as better information regarding the general health of individuals. Thus, such vital-sign monitoring systems will reduce health-care costs by disease prevention and enhance the quality of life with disease management. In this paper, recent progress in non-invasive monitoring technologies for chronic disease management is reviewed. In particular, devices and techniques for monitoring blood pressure, blood glucose levels, cardiac activity and respiratory activity are discussed; in addition, on-body propagation issues for multiple sensors are presented.

This paper reviews non-invasive blood glucose measurements via dielectric spectroscopy at microwave frequencies presented in the literature. The intent is to clarify the key challenges that must be overcome if this approach is to work, to suggest some possible ways towards addressing these challenges and to contribute towards prevention of unnecessary ‘reinvention of the wheel’.

Tissue mimicking phantoms (TMPs) replicating the dielectric properties of wet skin, fat, blood, and muscle tissues for the 0.3 to 20 GHz frequency range are presented in this paper. The TMPs reflect the dielectric properties with maximum deviations of 7.7 units and 3.9 S/m for relative dielectric constant and conductivity, respectively, for the whole band. The dielectric properties of the blood mimicking material are further investigated by adding realistic glucose amounts and a Cole-Cole model used to compare the behavior with respect to changing glucose levels. In addition, a patch resonator was fabricated and tested with the four-layered physical phantom developed in house. It was observed that the input impedance of the resonator is sensitive to the changes in the dielectric properties and, hence, to the realistic glucose level changes in the blood layer.

Radio-frequency identification (RFID) is a growing technology, with the potential for reducing medical errors and improving the quality of healthcare in hospitals. The benefits include more secure and safe access in the healthcare environment (with the possibility, for example, to track patients, personnel, and equipment), as well as providing the means to easily identify patients and their medications with low risk of error. In this paper, we present an overview of the challenges faced in antenna design, electromagnetic modeling and wave propagation for RFID implants. The performance of ultra-high-frequency (UHF) subcutaneous tag antennas was investigated numerically and validated with measurements. Furthermore, the wave propagation between an off-body reader and an implanted tag was analyzed, in both free space and a scattered indoor environment. Results demonstrated that a passive tag solution allows a very limited communication range, due to the body losses, the electrically small size of the antenna, and nulls in the radiation pattern. In comparison, a maximum communication range of 10 m was predicted as achievable for an active tag operating indoors with a limited power (-20 dBm).

An analytical formulation for relative dielectric constant retrieval is reconstructed to establish a relationship between the response of a spiral microstrip resonator and effective relative dielectric constant of a lossy superstrate, such as biological tissue. To do so, an analytical equation is modified by constructing functions for the two unknowns, the filling factor A and effective length leff of the resonator. This is done by simulating the resonator with digital phantoms of varying permittivity. The values of A and leff are determined for each phantom from the resulting S-parameter response, using particle swarm optimization. Multiple nonlinear regression is applied to produce equations for A and leff, expressed as a function of frequency and the phantom's relative dielectric constant. These equations are combined to form a new nonlinear analytical equation, which is then solved using the Newton-Raphson iterative method, for both simulations and measurements of physical phantoms. To verify the reconstructed dielectric constant, the dielectric properties of the physical phantoms are determined with commercial high temperature open-ended coaxial probe. The dielectric properties are reconstructed by the described method, with less than 3.67% error with respect to the measurements.