Design and implementation of an optimised wireless pressure sensor for biomedical application

This paper presents design and implementation of a wireless pressure sensor system for biomedical application. The system consists of a front-end Micro-Electro- Mechanical System (MEMS) sensing capacitor along with an optimised MEMS-based oscillator for signal conditioning circuit. In this design, vertical fringed comb capacitor is employed due to the advantages of smaller area, higher linearity and larger full scale change in capacitance compared to parallel plate counterparts. The MEMS components are designed in Coventorware design suite and their Verilog-A models are extracted and then imported to Cadence for co-simulation with the CMOS section of the system using AMI 0.6-micron CMOS process. In this paper, an optimisation method to significantly reduce the system power consumption while maintaining the system performance sufficient is also proposed. A phase noise optimisation approach is based on the algorithm to limit the oscillator tail current. Results show that for the pressure range of 0–300 mmHg the device capacitance range of 1.31 pF – 1.98 pF is achieved which results in a frequency sweep of 2.54 GHz – 1.95 GHz. Results also indicate that a 42% reduction of power consumption is achieved when the optimisation algorithm is applied. This characteristic makes the sensor system a better candidate for wireless biomedical applications where power consumption is the major factor. Hai Phuong Le received his B.E. (Hons) degree in Electronic and Computer System Engineering from University of Tasmania, Hobart, Australia in 2000. He received his Ph.D. degree in Microelectronics from Victoria University, Melbourne, Australia in 2005. At present, he is a post-doctoral research fellow and lecturer in the Centre for Telecommunications and Microelectronics, Victoria University. His research and teaching interests include data acquisition system, mixed-signal integrated circuit design and wireless smart sensor systems. Kriyang Shah received his B.E. Degree in Electronics and Communication Engineering from Sardar Patel University, Vallabh Vidyanagar, Gujarat, India and his Master Degree in Microelectronics in 2004. He is currently a Ph.D. research student in the Centre for Telecommunications and Microelectronics, Victoria University, Melbourne, Australia. His research interests include MEMS Sensors, RF MEMS, process integration for MEMS and CMOS and MEMS-CMOS co-simulation. Jugdutt (Jack) Singh received his B.Sc. in Electronics Engineering from University of Brighton, UK and M.Sc. in Electronics Engineering from University of Alberta, Canada in 1978 and 1986 respectively. He completed his Ph.D. at Victoria University, Australia in 1997. Since 1989 he has been at Victoria University, Melbourne, Australia. Currently he is a Professor of Microelectronics in the Centre for Telecommunications and Microelectronics at Victoria University. His major area of research interests are in the RF, analog and mixed signal design, reconfigurable architectures, low power VLSI circuits and systems design. He has published number of articles in education and research in microelectronics and small technologies area. Aladin Zayegh received his B.E. degree in Electrical Engineering from Aleppo University in 1970 and Ph.D. degree from Claude Bernard University, France in 1979. In 1980, he joined the Faculty of Engineering, Tripoli, Libya. Since 1984 he has held lecturing position at Victoria University, Melbourne, Australia. He is currently an Associate Professor and the Head of School in the School of Electrical Engineering, Faculty of Health, Engineering and Engineering and Science at Victoria University. His research interest includes microprocessor-based system, instrumentation, data acquisition and interfacing, and microelectronics.