A Thick Film Resistor Network for Sensor Applications
Strain, temperature, pressure, position, flow and the presence of specific chemicals are the properties that can be measured using sensors manufactured using thick film resistor network circuits.
Thick film materials are ideally suited to sensor applications due to their robust nature, precise tolerances and resistance to mechanical, thermal and chemical puts strain on. Thick film resistors, particularly resistor networks, may be utilized in a variety of sensors as follows:
The most widely used characteristic that varies in proportion to strain is electrical resistance. Piezoresistive properties of thick-film resistor inks are often used to form strain sensors as the thick film structure can be achieved sensitive to strain creating a change in resistance.
The ideal strain gauges would change resistance only due to the deformations of the surface which the sensor is positioned. However, in real applications temperature, material properties, the adhesive that bonds the gauges to the surface, and the stability belonging to the metal all affect the detected resistance. Hence, hitting the ground with thick film resistor network manufacturing technology and materials is vital in visuals and manufacture of stress gauge suitable for a particular application.
Consideration of temperature is vital as it can be cause a quantity of effects including alternation in size of the article due to thermal expansion, change typically the resistance of the gauge and the resistance of the connecting wires all contributing to a misreading of the applied strain. Unfortunately, the most desirable strain gauges materials are also understanding of temperature variations and may change resistance as time passes.
The linear temperature coefficient of resistance possessed by certain platinum-containing conductive inks has allowed thermistors to be printed onto suitable substrates using thick-film fabrication techniques. Thick-film thermistors are very inexpensive and physically small, and have the further advantage for being more intimately bonded to the substrate than a discrete component. Thick film sensors are generally linear, but this depends upon the Ohmic value of the sensor element although decade values change more than others at very low or very high temperatures.
Thick film resistor technology pressure sensors have higher stability than the semiconductor technology equivalent. When subjected to temperature cycling and aging tests a thick film resistor network will remain stable without any significant measurable change in resistance.
A appropriately designed thick film resistor network can therefore find application in a wide array of sensor applications but appropriate hitting the ground with both materials and manufacturing is found it necessary to produce a device with the required performance under a variety of environmental stress predicaments.