This paper reports on molecular sensing layer design of a piezoresistive cantilever sensor for higher surface stress sensitivity. The proposed analyses show that the previous understanding of piezoresistive cantilevers for surface stress measurement requires reconsideration for a cantilever utilizing polycrystalline silicon as a piezoresistor. | Vietnam Journal of Mechanics, VAST, Vol. 34, No. 4 (2012), pp. 311 – 320 MOLECULES SENSING LAYER DESIGN OF PIEZORESISTIVE CANTILEVER SENSOR FOR HIGHER SURFACE STRESS SENSITIVITY Tsung-I Yin, Tien Anh Nguyen University of Freiburg, Germany Abstract. This paper reports on molecular sensing layer design of a piezoresistive cantilever sensor for higher surface stress sensitivity. The proposed analyses show that the previous understanding of piezoresistive cantilevers for surface stress measurement requires reconsideration for a cantilever utilizing polycrystalline silicon as a piezoresistor. The integration of the molecular sensing layer stripe pattern design to the cantilever effectively improves the piezoresistive output and utilizes the full sensing area of the cantilever surface. The proposed sensing layer design can be effectively integrated to current piezoresistive cantilever sensors to improve sensor performance in biochemical assays. Keyword: piezoresistive cantilever sensors, surface stress sensitivity, biochemical assays. 1. INTRODUCTION Surface stress is a well-known property of a solid surface [1]. Recently, a cantilever has been applied as a versatile biochemical sensor for measurement of surface stress induced by hybridization of DNA, antibody-antigen binding, small ion detection, toxic gas detection, and intermolecular interaction of self-assembling monolayers [2]. Different detection methods, including optical levers [3], as well as piezoresistive [4], piezoelectric [5], capacitance [6], and MOSFET devices [7], have been developed to measure the cantilever deflection induced by surface stress change. Due to the prevalence of piezoresistors in the current sensor market and their inherent advantages in microsystem integration, such as in microfluidic parts, piezoresistive detection is highly attractive in cantilever sensor design. However, the accompanying electrical noise in sensor operation, . 1/f noise, poses a serious limitation to their .
