Ranjith Amarasinghe

Design and fabrication of a miniaturized six-degree-of-freedom piezoresistive accelerometer

This paper presents a miniaturized six-degree-of-freedom (6-DOF) piezoresistive accelerometer. The accelerometer is capable of measuring three components of linear acceleration and three components of angular acceleration on three orthogonal axes at the frequency bandwidth of 300 Hz. The obtained experimental results showed good agreement with the finite element simulation. The sensor is ideal for use in biomechanical research applications requiring detection of multiple components of acceleration such as the study of human gesture recognition systems.

Simulation, fabrication and characterization of a three-axis piezoresistive accelerometer

This paper presents a miniaturized three-axis piezoresistive accelerometer using bulk micromachining technology. The accelerometer consists of a highly symmetric single-crystalline silicon crossbeam structure with 12 conventional two-terminal p-type piezoresistors diffused on the surface of the beams. The die size of the acceleration chip is 3 mm × 3 mm. In addition, it is significantly smaller than those of previously presented approaches. It measures three components of acceleration up to ± 10 g on three orthogonal axes simultaneously. The average measured sensitivities of the fabricated sensor for accelerations Ax, Ay, Az on the X, Y, Z axes are about 1.14, 1.15, 0.98 mV (V g)−1 respectively. The measurement results show a cross-axis sensitivity of <4%. This sensor is designed for use in biomechanical research applications such as human gesture recognition systems.

Design and fabrication of miniaturized six-degree of freedom piezoresistive accelerometer

This paper reports a novel miniaturized piezoresistive six-degree of freedom (6DOF) accelerometer designed and fabricated using bulk micromachining technology. This accelerometer measures three components of linear acceleration and three components of angular acceleration on three orthogonal axes in the frequency bandwidth of 300Hz. The average measured sensitivities of the fabricated sensor for linear accelerations and angular accelerations show a cross-axis sensitivity of >4%. Comparison of the obtained experimental results and finite element simulation shows good agreement. The sensor is ideal for use in biomechanical research applications such as study of human gesture recognition systems.

Microfluidic valveless pump actuated by electromagnetic force

This paper presents the study on displacement valveless micropump which is actuated by electromagnetic force on a permanent magnet embedded in PDMS diaphragm. The network channel of the present pump includes two inlets and one outlet channels forming an intersection in front of a pump chamber. Two designs of the pump with different structure of the inlet channels are investigated. One structure of the inlet is curved around the pump chamber (type I) and the other is straight channels (type II). Both types of pump are in one layer structure. The numerical simulation results show that Type I produces larger flow rate than that of Type II. However, at small deflection of the diaphragm, the difference in flow rates between two pumps is not much. Type I shows a clear advance pump performance in comparison with Type II when deflection becomes large. Type I has been fabricated by MEMS technology for experiment study. The fundamental characteristics of the pump have been validated. The flow rate of up to 1.2 mL/min was obtained at driven frequency of 30Hz and applied current of 35 mA.

Sensitivity enhancement of piezoresistive micro acceleration sensors with Nanometer Stress Concentration Regions on sensing elements

This paper presents a novel approach for considerably enhancing the sensitivity of piezoresistive microcantilever-type acceleration sensors. The design, fabrication and characterization of an ultra miniature single crystal micro acceleration sensor with Nanometer Stress Concentration Region (NSCR) on piezoresistors utilizing bulk micromachining techniques and Focus Iron Beam tool (FIB) have been discussed. Finite element simulations indicate an increase in sensitivity compared to a conventional microcantilever beam with the same thickness by a factor of 8.6. Devices have been fabricated and initial characterization has been performed. The new design shows an increase in the relative resistance change compared to a microcantilever with the same thickness and conventional piezoresistor design.

Ultra miniature novel three-axis micro accelerometer

This paper presents for the first time the design, fabrication and characterization of an ultra miniaturized novel 3-axis accelerometer with nanoscale piezoresistive sensing elements and read out circuits. It was developed using MEMS/NEMS machining and fabrication techniques. This sensor consists of a new sub-millimeter structure with seismic mass and combined cross-beam and surrounding beams. It can detect three components of linear acceleration simultaneously. The sensitivity could be enhanced significantly while miniaturizing the die size of sensor chip with aid of novel structure and nanoscale piezoresistors on the sensing beams. Therefore, this novel proposed sensor is showing good performance and smaller than other comparable miniaturized sensor structures reported thus far. The accelerometer is capable of measuring accelerations up to ±20g in the frequency bandwidth of 480Hz. Comparison of the obtained experimental results and finite element simulation shows good agreement.

Development of PZT Actuated Valveless Micropump

A piezoelectrically actuated valveless micropump has been designed and developed. The principle components of this system are piezoelectrically actuated (PZT) metal diaphragms and a complete fluid flow system. The design of this pump mainly focuses on a cross junction, which is generated by a nozzle jet attached to a pump chamber and the intersection of two inlet channels and an outlet channel respectively. During each PZT diaphragm vibration cycle, the junction connecting the inlet and outlet channels with the nozzle jet permits consistencies in fluidic momentum and resistances in order to facilitate complete fluidic path throughout the system, in the absence of any physical valves. The entire micropump structure is fabricated as a plate-by-plate element of polymethyl methacrylate (PMMA) sheets and sandwiched to get required fluidic network as well as the overall device. In order to identify the flow characteristics, and to validate the test results with numerical simulation data, FEM analysis using ANSYS was carried out and an eigenfrequency analysis was performed to the PZT diaphragm using COMSOL Multiphysics. In addition, the control system of the pump was designed and developed to change the applied frequency to the piezoelectric diaphragms. The experimental data revealed that the maximum flow rate is 31.15 mL/min at a frequency of 100 Hz. Our proposed design is not only for a specific application but also useful in a wide range of biomedical applications.

Design and Fabrication of a Miniaturized Three-Degree-of-Freedom Piezoresistive Acceleration Sensor Based on MEMS Technology Using Deep Reactive Ion Etching

This paper presents the design and the fabrication of a miniaturized three-degree-of-freedom piezoresistive acceleration sensor based on MEMS technology using deep reactive ion etching. Finite element method (FEM) using the ANSYS program has been applied to study the mechanical and electrical behavior of the device. The fabricated sensor with the dimension 1 × 1 × 0.45 mm3 can detect simultaneously three components of the linear acceleration at the frequency bandwidth 100 Hz.

Design and Simulation of Piezoresistive Micro Accelerometers for Wearable Sensing Applications

This paper presents the modeling and simulation of new structure for solid-state three degrees of freedom (3-DOF) micro accelerometer utilizing piezoresistive effect in single crystal Si. The proposed sensor can detect three components of linear acceleration simultaneously. The sensing structure consists of combined cross-beam and surrounding beams and seismic mass. Therefore, this novel proposed sensor is showing good performance than other miniaturized sensor structures reported thus far.

Design a Fabrication of Piezoresistive Six Degree of Freedom Accelerometer for Biomechanical Applications

A miniaturized piezoresistive six-degree of freedom (6DOF) accelerometer has been developed and fabricated using bulk micromachining technology. Most accelerometers developed so far, sense accelerations in only three axial directions. This accelerometer measures three components of linear acceleration and three components of angular acceleration on three orthogonal axes in the frequency bandwidth of 300Hz. The average measured sensitivities of the fabricated sensor for linear accelerations and angular accelerations show a cross-axis sensitivity of <2%. Comparison of the obtained experimental results and finite element simulation shows good agreement. The sensor is ideal for use in biomechanical research applications such as the study of human gesture recognition systems.