Prescon sensors are available with a variety of substrates.  Polyester, polycarbonate, vinyl, polyurethane, PVC, polyimides, printed circuit board, glass, alumina, beryllia, thermistor, resistor and capacitor substrates.  It is also possible to have combinations of the above for specialized applications (e.g., pcb and polyester).

Sensor Exposure to Operating Conditions

The pressure sensors should be pretested in their load-life environmental application.  The user will obtain data once the sensor has been pretested, giving performance characteristics for the particular sensor and its design in the application.  The characteristics of the data then gives a prediction of the electrical parameters that can be expected from sensor operation.
The following parameters are normally associated with pressure sensors:

1.	Variable ohmic response with variable pressure
2.	Ohmic response range for pressure being applied versus ohmic response for pressure being removed
3.	Ohmic response range (tolerance and drift) for a constant pressure over extended time periods.

Once the user has determined the output parameters for the Prescon sensor design, application, and environment, the user has established the general operating characteristics for the system requirement.

Electrical Performance and Operating Considerations

Prescon pressure sensors convert applied pressure to an electronic transmission signal in ohms resistance.  When pressure is applied to the active sensing area of the sensor, the sensor will transmit a resistance reading to the system instrumentation.  Pressure to the sensor's active area can be applied by finger touch, any type of stylus, or by mechanical or robotic systems.  The area of the activator (finger or stylus) should correspond closely to the active area of the sensor otherwise erroneous results will be obtained.

The basic instrumentation generally can be composed of multiplexers, analog/digital converters, microprocessors, display drivers and displays.

In most applications with no pressure applied, Prescon sensors will show infinite resistance (e.g., an open circuit).  When the activation threshold pressure is applied to the sensing area, the sensor will turn on and activate, closing the circuit and start to give a resistance reading in ohms.  As pressure is increased, the resistance reading will decrease.  Response time from pressure applied to signal generation is usually very short. Response times are in the ranges of .01 to .001 seconds.  All parameters associated with the sensor, such as design and operating environment will effect the response time and sensitivity of the sensor in its application.  Some features of the Prescon sensors will allow the response time to be changed in certain applications and requirements.  Since there are a multiple of electronic systems and interfaces that are utilized in Prescon pressure sensor applications and requirements, please contact our Advanced Technology Center staff if technical assistance is required in systems and interfaces.

Sensor Temperature Limits

Prescon sensors operate over a  range of temperatures depending on materials used.  Typically, the temperature limits are between -60°C and 130°C.  Other Prescon sensors constructed with different materials go beyond the 130°C limit.  Contact IMR for temperature requirements.  The limits depend on the sensor design and materials.  Slight variations of the sensor's sensitivity is dependent upon the temperature and the amount of pressure applied at that same temperature.  For accurate results it is best to test the sensor at the specific temperature or the temperature range through which it will be used in the application.

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