Monday, September 20, 2010

pressure sensors

Looking at converting a digital barometer to analogue in some manner. Need to develop a simple digital/analogue device, a device in registering something. Could be sound, inaudible at such a slow rate of change but compressed in time to make something more present.
A pressure sensor to act like a breathing mechanism, like lungs breathing as pressure changes, a heart beat is pressure changing. Flexing a material - becomes a system in and of itself. The approach of an observer changes the absolute pressure of the space, therefore no longer just being the observer but becoming part of of the environment.
Kinds of pressure: absolute
differential -moving from a high pressure to a low pressure can carry a force that can be converted to an electrical current - energy
gauge
(switch)
vacuum
Miniature Pressure Transducer
-designed to minimize sensor size while maintaining usable bandwidth.
-a foil strain gauge is coupled to a flat support plate, which is then mounted to the edges of a dome-like cover. When pressure is applied to the MPT, the support plate deforms, elongating the strain gauge.
-may need to connect to a Wheatstone bridge circuit to maximize the output of the sensor. This is the most commonly employed sensing technology for general purpose pressure measurement. Generally, these technologies are suited to measure absolute, gauge, vacuum, and differential pressures.
Altitude Sensing
-uses the relationship between changes in pressure relative to the altitude. Barometric pressure sensors can have an altitude resolution of less than 1 meter.
Strain Gauge Sensor
- simple accurate way to measure even sight deformation of a solid surface or object.
-Classified by material - usually a bended wire, metal foil, as a semiconductor
physical size
resistance
gauge factor - defined as the ration of the fractal change in resistance over the fractional change in length along the gauge axis
Force Sensitive Resistor (FSR)
-forcing sensing resistor has a variable resistance as a function of applied pressure therefore making it more of a pressure sensor.
Piezoelectricity - piezoelectric effect
-many materials exhibit piezoelectricity - biological tissues, ie. tendons, intestine, silk, bone, and wood
sensorwiki.org - exploration of various sensors

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