Pyroelectric infra-red detector arrays provide an attractive solution to the problem of collecting spatial information on the IR distribution in a scene. They have the property that they are only sensitive to changes in the IR flux. This means that they are particularly-well suited to the monitoring of movements of people in applications such as retail outlets and in safety and healthcare applications. The applications of low cost arrays with limited (few hundred elements) for people sensing and imaging radiometry will be illustrated. The performances and costs of uncooled pyroelectric arrays are ultimately driven by the materials used. For this reason, continuous improvements in materials technology are important. In the area of bulk ceramics, it is possible to obtain significant improvements in both production costs and performance though the use of tape-cast, functionally-gradient materials. The use of directly-deposited ferroelectric thin films on silicon ASIC’s is offering considerable potential for low cost high performance pyroelectric arrays. The challenges involved in developing such materials will be discussed.