Development and Performance Evaluation of Double Bending Beam Force Transducer for Low-Force Measurement

Precision and traceable measurement of small forces have become increasingly important due to the rapid change in technology and miniaturization of devices. In this paper, we have discussed the design, development and metrological aspects of double bending beam force transducer for low-force measurements. To achieve this task, elastic spring element is designed and machined for fabricating the force transducer and virtually tested through the finite element analysis (FEA) method to validate its load capacity and to understand its mechanical behaviour. The metrological capability of spring element is determined with the application of small forces, sensing the applied forces through contact and non-contact methods. In the contact method, strain gauges are employed for the detection of induced strain on the spring element. For this, the maximum and minimum strain values and their distribution are found to get the optimum normalized output in the electrical unit of mV/V. In the non-contact method, a pair of light-emitting diode (LED) and light-dependent resistor (LDR) is utilized for the detection of the bending caused by the applied force. The optimal detectable deflection is found in the spring element through FEA. The experimental characterization results of the force transducers showed that the developed force transducers have good metrological capability in terms of high linearity and repeatability in the range of 0.3-3 N.