In the last decade, microelectromechanical systems(MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications,especial...In the last decade, microelectromechanical systems(MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications,especially in the field of chemical and biological sensing.Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times,numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail.In addition to the design-, fabrication-, and performancerelated factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.展开更多
For operation and manipulation with nanometric positioning precision,an integrated micro nano-positioning xy-stage is developed,which is mainly composed of a silicon-based xy-stage,comb-driven actuator and displacemen...For operation and manipulation with nanometric positioning precision,an integrated micro nano-positioning xy-stage is developed,which is mainly composed of a silicon-based xy-stage,comb-driven actuator and displacement sensor.The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching (DRIE) in both sides of wafer.The displacement sensor is mainly composed of four vertical sidewall surface piezoresistor connected to form a full Wheatstone bridge.A simple vertical sidewall surface piezoresistor process which improves on the basis of the conventional surface piezoresistor technique is proposed.The experimental results verify the integrated micro nano-positioning xy-stage including the vertical sidewall surface piezoresistor technique.The sensitivity of the fabricated piezoresistive sensors is better than 1.17 mV/μm without amplification and the linearity is better than 0.814%.Under 30 V driving voltage,a ±10 μm single-axis displacement is measured without crosstalk.The displacement resolution of the micro xy-stage is better than 10.8 nm.展开更多
文摘In the last decade, microelectromechanical systems(MEMS) SU-8 polymeric cantilevers with piezoresistive readout combined with the advances in molecular recognition techniques have found versatile applications,especially in the field of chemical and biological sensing.Compared to conventional solid-state semiconductor-based piezoresistive cantilever sensors, SU-8 polymeric cantilevers have advantages in terms of better sensitivity along with reduced material and fabrication cost. In recent times,numerous researchers have investigated their potential as a sensing platform due to high performance-to-cost ratio of SU-8 polymer-based cantilever sensors. In this article, we critically review the design, fabrication, and performance aspects of surface stress-based piezoresistive SU-8 polymeric cantilever sensors. The evolution of surface stress-based piezoresistive cantilever sensors from solid-state semiconductor materials to polymers, especially SU-8 polymer, is discussed in detail. Theoretical principles of surface stress generation and their application in cantilever sensing technology are also devised. Variants of SU-8 polymeric cantilevers with different composition of materials in cantilever stacks are explained. Furthermore, the interdependence of the material selection, geometrical design parameters, and fabrication process of piezoresistive SU-8 polymeric cantilever sensors and their cumulative impact on the sensor response are also explained in detail.In addition to the design-, fabrication-, and performancerelated factors, this article also describes various challenges in engineering SU-8 polymeric cantilevers as a universal sensing platform such as temperature and moisture vulnerability. This review article would serve as a guideline for researchers to understand specifics and functionality of surface stress-based piezoresistive SU-8 cantilever sensors.
基金Funded by the High Technology Research and Development Programme of China (2007AA04Z315)
文摘For operation and manipulation with nanometric positioning precision,an integrated micro nano-positioning xy-stage is developed,which is mainly composed of a silicon-based xy-stage,comb-driven actuator and displacement sensor.The high-aspect-ratio comb-driven xy-stage is achieved by deep reactive ion etching (DRIE) in both sides of wafer.The displacement sensor is mainly composed of four vertical sidewall surface piezoresistor connected to form a full Wheatstone bridge.A simple vertical sidewall surface piezoresistor process which improves on the basis of the conventional surface piezoresistor technique is proposed.The experimental results verify the integrated micro nano-positioning xy-stage including the vertical sidewall surface piezoresistor technique.The sensitivity of the fabricated piezoresistive sensors is better than 1.17 mV/μm without amplification and the linearity is better than 0.814%.Under 30 V driving voltage,a ±10 μm single-axis displacement is measured without crosstalk.The displacement resolution of the micro xy-stage is better than 10.8 nm.
