Research work carried out at the University of Bristol could have major benefits for the deployment of electronic devices in harsh environments, such as those experienced in the nuclear industry. The new work could pave the way for devices which can withstand much higher radiation levels and temperatures than is currently possible.
Breakthrough in the design of microelectromechanical relays
In collaboration with the University of Southampton and Microsemi, Dr Sunil Rana (Senior Research Associate) and Dr Dinesh Pamunuwa (Reader in Microelectronics) in the Department of Electrical and Electronic Engineering have made a breakthrough in the design of microelectromechanical relays. Relays offer an alternative to solid-state transistors (which have been the “workhorse” of the microelectronics industry for decades). Transistors are limited in their application because of leakage of electrical current when they are operated at high temperatures. In addition, transistors can only withstand relatively low levels of ionising radiation.
Relays offer the possibility of overcoming these temperature and radiation challenges. However, one of the drawbacks of relays is that the relay tips can become degraded over millions of switching cycles, therefore reducing the reliability of the electrical contact. The new research work has showed that the relay tips can be protected against degradation by coating them with films of nanocrystalline graphite. This coating, which is tens of nanometres thick, acts like a solid lubricant, protecting the tips as they physically make and break contact millions of times.
Applications across industrial sectors
Dr Pamunuwa: “This is a breakthrough result that could have applications across many industrial sectors. The increased tolerance to high radiation levels and high temperatures is likely to be of particular interest to the nuclear industry; the graphite-coated relays can withstand radiation levels which are up to three orders of magnitude greater than is possible with transistors. This work could help enable deployment of electronic devices with longer battery life and less shielding than can currently be achieved.
We now plan to expand the scope of our research from individual relays to whole circuits. We look forward to engaging with nuclear industry partners to consider further development of this technology and potential deployment in both operational nuclear plants and decommissioning situations.”
Research Paper
'Nano-crystalline graphite for reliability improvement in MEM relay contacts' by Sunil Rana, Jamie D. Reynolds, Ting Y. Ling, Muhammed S. Shamsudin, Suan Hui Pu, Harold M.H. Chong and Dinesh Pamunuwa in Carbon