A RF wireless capacitive pressure sensor is developed. The sensor has integrated inductor with the pressure sensitive
capacitor as LC circuit. The resonant frequency of the sensor changes as the capacitance changes with applied pressure.
The sensor uses LPCVD silicon nitride as sensitive membrane and the residual stress of the membrane has been measure
as 139MPa. The sensor has size of 10 mm × 4 mm × 0.5 um. The sensor presents a pressure sensitivity of 1.65
MHz/cmH2O in pressure range of 0-20 cmH2O. The deflection of different shape of membranes is discussed. The
deflection of square membrane is 130% to circular membrane under same applied pressure.
A RF wireless capacitive flow sensor is developed. The sensor has integrated inductor with the flow sensitive capacitors
as LC circuit. The resonant frequency of the sensor changes as the capacitance changes with applied flow. The sensor
uses LPCVD silicon nitride as sensitive membrane and the residual stress of the membrane has been measure as 139
MPa. The sensor has size of 10 mm × 4 mm × 0.5 μm. The sensor integrated two pressure sensors together and designed
related to flow 5-20ml/hour. The deflection of different shape of membranes and the parameters of flow sensor
sensitivity are discussed. The deflection of square membrane is 130% to circular membrane under same applied
pressure.
A 1D IR lock-in focal plane array (FPA) for extremely weak signal imaging has been demonstrated. The experimental system consists of an object with modulated image signal, a high speed InGaAs linear photodetector array as receiver, a CMOS lock-in linear array read-out circuit, and a focal plane array test system. The system can detect extremely weak signals immersed in strong background. Preliminary test shows that under room temperature each of the pixels in the 1D lock-in FPA can read out modulated signal 5 orders smaller than the background. The InGaAs detector array response is
from 0.8 μm to 1.6 μm (peak at 1.2 μm). The lock-in array read-out circuit uses a correlated multi-cycle integrator, which can operate in several modes such as gated integration, and phase-sensitive integration with background subtraction. The 1D lock-in FPA works as a pixel to pixel lock-in amplifier, wherein very small signals may be extracted from a much strong background if the frequency of the illuminating source (usually IR light sources) is known. Simulation results are also reported. Experimental results based on an IR illuminating source are demonstrated.
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