The structured circuit board printed with conductive polymer of a high gauge factor allows for customized bending bar DMS applications. A bending bar can be milled from a circuit board (FR4). The resistor layers are printed on both sides onto the zones of the bending bar that have the most stress – they can be determined by means of a finite element analysis. The printing and tensile load of the resistor layer causes a change in resistance. The completely symmetric design on the upper and lower side creates a small temperature coefficient of the sensor signal. Such polymer bending bars achieve an offset of less than 100 ppm/K and a sensitivity temperature coefficient of under 30 ppm/K.
The sensitivity of the polymer DMS is more than one order of magnitude greater than with conventional strain gauges. Due to the higher resistances of the testing bridge, the polymer DMS consumes far less electricity. Designing the circuit of the resistors as a Wheatstone bridge creates an ideal signal strength and temperature compensation.
Overview of advantages
- Robust bending bars with polymer DMS (force and pressure sensors)
- Simple integration of the sensor and electronics on one circuit board
- Customized designs (form, sensitivity, force measurement range)
- High sensitivity – low amplification required
- Low consumption of electricity – stand-alone solutions are possible
- Ideal as shortcut switch (mm path) with haptic feedback
Matched to your requirements, we can provide solutions that offer very fast signal processing or a high degree of sensitivity. A major technological advantage of the polymer-DMS bending bar solution over conventional DMS (strain gauges) is their low consumption of electricity. This makes stand-alone systems possible.