| Summary: | In an attempt to provide a more secure and amiable living environment in our
homes, there has been constant effort to develop more efficient and suitable intelligent
sensor technology for household application. Wireless sensors provide an efficient
means of sensing without the need for messy wiring, and are ideally suited for the
household environment. Although many sensor products have been developed (e.g.
temperature, humidity and smoke), automated detection and reporting of an incidence
occurring in places hard to observe or reach, such as wetting of diapers or water seepage
under carpets, are still not readily available at low cost. Most of the existing
technologies consist of complex design architecture and follow specific communication
protocols which can be overkill for many simple household applications.
In this thesis, we present a new wireless sensor system which is based on the
detection of just the ON or OFF state of a condition. This approach overcomes the need
for complex architecture and design, but is still able to achieve the functionality that is
required for many household applications such as water leakage, food rotting, diaper
wetting etc. and thus can be made available very cheaply.
The sensor system consisting of an interrogator and a sensor circuit is
implemented using inductive coupling. A passive L-C circuit is used for the sensor design and the system is tested using diaper wetting as an example of a simple household
application. The testing results shows that the sensor can detect an ON and OFF
condition for sensor and tag separation of 10 cm which is enough for applications like
water leakage behind walls and under carpets, diaper wetting, food rotting etc.
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