Effect of Different Wheatstone Bridge Configurations on Sensitivity and Linearity of MEMS Piezoresistive Intracranial Pressure Sensors

Monitoring of intracranial pressure for traumatic brain injured patients is very critical.  Many intracranial pressure monitoring systems use the MEMS piezoresistive pressure sensor to measure the signal.  The piezoresistive pressure sensor is very sensitive to temperature change.  Hence, the Wheatstone bridge circuit is normally employed in this type of sensor to lessen the effect of temperature variation.  This paper presents the effect of using different configurations of Wheat-stone bridge on the sensitivity and linearity performances of the piezoresistive intracranial pressure sensor.  Six designs comprise of 3-turns meander shaped piezoresistors ranging from full-bridge to quarter-bridge were simulated using COMSOL Multiphysics.  Based on the simulation results, the number and position of active piezoresistors were found to greatly influence the sensitivity of the sensor.  The latter also influenced the sensors’ linearity error.  The active perpendicular piezoresistor produced the higher change in resistance which gave rise to higher sensitivity, while at the same caused the higher nonlinearity performance.  Overall, the piezoresistive intracranial sensor comprises of full-bridge Wheat-stone circuit produces the highest sensitivity and medium linearity

Intelligent car detecting system (ICDS)

In this modern life, with the prosperous economy we are experiencing, most people own at least one car. Cars have been used widely as a mean of our daily transportation to help us commute from one place to another. As people are becoming so involved with their hectic schedule, sometimes they could not remember where they have parked their cars. Thus, this project is done to help the car owner to locate the distance of the car from his current location. The project uses the half-duplex communication between two units of transceivers, MOBILE unit and FIXED unit to provide the location of the car. The principle of RFID is applied in this project by assigning each unit with unique ID number. The FIXED unit is placed inside the car while the MOBILE unit is kept by the owner. The latter unit does the computation of the location estimation based on the signal it received from the FIXED unit. The estimation of location is done based on the received signal strength formulation. The free space path loss has been assumed. From this received signal strength which is also equivalent to R V 2 , the inverse proportionality of voltage level and distance is used in the calculation. The accuracy of the system is found to be in the range of 0.0m to 50.0m. The accuracy is found to degrade with the further the distance is. The large number is due to the limitation of the formulation used. The system is able to detect the location of the car within 250m radiu