The optical sensor mote, a novel device for enabling next generation Wireless Sensor Networks

Recent advances in micro-electronics and communications have fuelled research in Wireless Sensor Networks (WSNs). WSNs are a collection of low power, low cost, small form factor devices referred to as sensor motes interconnected in a random manner to establish a network. Despite wide ranging research into a range of applications, significant limitations stand in the way of utilizing WSNs to monitor large scale/area environments. Optical sensing techniques are well suited for monitoring a large variety of environmental variables such as temperature, pressure, humidity, and gas concentrations. However, traditional optical sensing techniques rely on bulky solutions including spectroscopic equipment and fibre based approaches. On the other hand, photonic crystals have caused a revolution in integrated optics as they allow functionalities not possible before; however little has been reported on their use as integrated optical sensors. The research work combines the diverse but related fields of WSNs, integrated optics, and Photonic Crystals. A novel platform, the optical sensor mote, is proposed and its key building blocks are experimentally demonstrated as a feasibility study. Specifically, multi-gas sensors based on the slow light phenomenon in photonic crystal waveguides are theoretically and experimentally demonstrated. These sensors can sense multiple gases without the need of any physical changes. They can also be integrated with electronics to yield an optical sensor mote of small form factor which is stable, multi-functional, and cost-effective. The optical sensor mote represents a significant step towards enabling the wide spread use of WSNs to monitor large scale/area environments and providing a highly integrated mote platform amenable to mass production and providing multi-functions.Recent advances in micro-electronics and communications have fuelled research in Wireless Sensor Networks (WSNs). WSNs are a collection of low power, low cost, small form factor devices referred to as sensor motes interconnected in a random manner to establish a network. Despite wide ranging research into a range of applications, significant limitations stand in the way of utilizing WSNs to monitor large scale/area environments. Optical sensing techniques are well suited for monitoring a large variety of environmental variables such as temperature, pressure, humidity, and gas concentrations. However, traditional optical sensing techniques rely on bulky solutions including spectroscopic equipment and fibre based approaches. On the other hand, photonic crystals have caused a revolution in integrated optics as they allow functionalities not possible before; however little has been reported on their use as integrated optical sensors. The research work combines the diverse but related fields of WSNs, integrated optics, and Photonic Crystals. A novel platform, the optical sensor mote, is proposed and its key building blocks are experimentally demonstrated as a feasibility study. Specifically, multi-gas sensors based on the slow light phenomenon in photonic crystal waveguides are theoretically and experimentally demonstrated. These sensors can sense multiple gases without the need of any physical changes. They can also be integrated with electronics to yield an optical sensor mote of small form factor which is stable, multi-functional, and cost-effective. The optical sensor mote represents a significant step towards enabling the wide spread use of WSNs to monitor large scale/area environments and providing a highly integrated mote platform amenable to mass production and providing multi-functions