Now showing 1 - 2 of 2
  • Publication
    Influence of Exposure Guidelines on the Design of On-Body Inductive Power Transfer
    Designers of on-body health sensing devices with inductive power transfer (IPT) face a number of trade-offs. Safe exposure limits should be maintained, and protective housing and padding are generally needed; however, these impose compromises on the power-transfer-system design. This paper analyses these trade-offs and proposes a design route to achieving high power transfer in the presence of field restrictions and separations for padding or housing materials. An IPT system using a Class D coil-driver and switched-mode power-conditioning is designed to provide regulated d.c. and energy storage. Compliance with ICNIRP 1998 guidelines is demonstrated, at a power level that is sufficient to power typical on-body medical sensing devices.
      272Scopus© Citations 3
  • Publication
    Inductive Power Transfer for On-body Sensors. Defining a design space for safe, wirelessly powered on-body health sensors
    Designers of on-body health sensing devices face a difficult choice. They must either minimise the power consumption of devices, which in reality means reducing the sensing capabilities, or build devices that require regular battery changes or recharging. Both options limit the effectiveness of devices. Here we investigate an alternative. This paper presents a method of designing safe, wireless, inductive power transfer into on-body sensor products. This approach can produce sensing devices that can be worn for longer durations without the need for human intervention, whilst also having greater sensing and data capture capabilities. The paper addresses significant challenges in achieving this aim, in particular: device safety, sufficient power transfer, and human factors regarding device geometry. We show how to develop a device that meets stringent international safety guidelines for electromagnetic energy on the body and describe a design space that allows designers to make trade-offs that balance power transfer with other constraints, e.g. size and bulk, that affect the wearability of devices. Finally we describe a rapid experimental method to investigate the optimal placement of on-body devices and the actual versus theoretical power transfer for on-body, inductively powered devices. 
      241Scopus© Citations 6