SAVVIE: Staying alive in variable, intermittent, low-power environments

Today's low-power electronic systems are designed to handle a high variability in the power demand, for example during transmissions from miniature wireless sensors. However these systems cannot cope with a highly variable power supply. If they are powered by an ambient energy harvester in an environment where the available power is low and sporadic, the system dies once the energy storage becomes depleted or damaged, with start-up being impossible if the power is not increased to a higher steady level. With an increasing number of potential applications of microelectronic systems calling for remote, embedded and miniaturized solutions, sporadic and low power supply and unpredictable energy storage needs to be addressed.

This project researches how to design robust and reliable electronics for situations where there is a variable, unreliable source of energy. A number of situations, or states, have been defined, according to the level of depletion of on-board energy storage, and to how variable the power supply is. In the most challenging states, for example where the input power is sporadic and spread over a wide range from nW to mW, modern electronics fails. We call this the "survival zone" and are investigating a combination of techniques from the areas of power electronics and asynchronous microelectronics design to allow devices to operate in this zone. Techniques include control circuits that are able to ride through variable voltages, the detection of states, and reconfigurable hardware resources and control algorithms to suit sporadic and sub-microwatt input power. The chief aim of this project is to produce survival zone design methods for the microelectronics design community.

SOCIETY
The scientific aims of the project support the development of unobtrusive healthcare and security devices and power saving techniques for electronic systems. Applications could be the enabling technologies for blanket monitoring of water supplies or wearable sensors for those with chronic illness. The transfer of results and skills to these areas will be carried out via joint projects, for example a large KTA project "Crossing the Clinical Boundary", placed at Durham/Newcastle, with direct links with practising heart surgeons and electro physiologists.

PEOPLE
This project brings together two areas of engineering, power electronics and microelectronic design, which are traditionally separate, providing the opportunity to learn and to create systems that do more computation with less power, and in particular sporadic power that is difficult to harness. This will create a common language for much needed systems engineers who work at the boundary of electrical power engineering and computing. Project staff will spend time at leading European research organisations, such as IMEC, providing the project team with manufacturing and additional research experience. The project will allow the project teams to train up PhD students in most recent techniques, and it will underpin University teaching of the increasingly important areas of energy-aware microelectronic design, and ultra-efficient power electronic control for miniature energy harvesting to domestic-scale renewable energy generation.

KNOWLEDGE
The developed techniques will enhance efficiency, operability and survivability of microelectronics in sporadic power situations which are currently inaccessible to modern electronics. The developed methods will be presented to the wider community in an international workshop in Month 33 of the project. Throughout the project, courses and tutorials will be delivered at conferences, as is current practice by team members already (for example at DATE 2010, DDECS 2010, ASYNC 2010). The first such dissemination tutorials for this project are at PATMOS'12 and UK Electronics Forum 2012, both hosted by Newcastle, and ESWEEK 2013.

ECONOMY
The project is supported by Texas Instruments (TI), a top multi-national hi-tech company and leader in semiconductor and power electronics markets. This collaboration will ensure that the work is targeted and relevant to the industry without compromising on the aspiration to create transformational enabling technologies for future devices. It will allow the results of the project to make direct impact on the energy-aware embedded system design methodology and electronics for energy harvesting sources and applications. The project plan includes an early physical demonstrator system, which will be used to prioritise challenges, with involvement from TI engineers. TI have supported previous projects at Bristol and introduced teams to their industrial research and manufacturing partners at key stages in research projects. Once concrete design tools have been established, UK companies will be used to commercialise results, for example Newcastle's recent spin out company i GXL, and also the UK companies and UK branches of international companies who are represented on Newcastle's and Bristol's Engineering advisory boards (e.g. Aptina, ARM, Cadence, Imagination, Sony, STMicroelectronics, TI, and Toshiba TREL).