The Development of a Passive, Wireless Sensor System

Today many sensor systems are available off the shelf and allow measurement of a wide range of environmental parameters such as humidity, temperature, pressure or the concentration of various chemical species. However, nearly all these sensor systems suffer from two potential drawbacks. The first is that they are active sensors, meaning that they are continuously powered and thus needs a constant power source such as a battery. This leads to limitations in terms of battery lifetime or in sensor mobility if it is powered from a fixed source. A second drawback of conventional sensor systems is the fact that direct physical contact in the form of electrical conductors is normally needed between the sensor and readout electronics. This places constraints on the configuration between readout electronics and the sensor element and limits the mobility of the sensor system. The aim of this work is to develop a sensor system that will overcome the two limitations described above, using technology commonly used in the prevention of shoplifting.