Semiconductor Strain Gauge Solutions
Most strain gauge-based sensors are constructed with metal foil-based strain gauges, typically made from a Constantan or Karma alloy. However, some sensors incorporate semiconductor strain gauges, which are usually made from silicon. Semiconductor strain gauges have a much higher gauge factor than standard foil gauges, so they are much more sensitive and suitable for low load measurements, but they are also more susceptible to temperature effects. ln addition to traditional foil strain gauge application support, HITEC offers extensive expertise and experience in the semiconductor strain gauge field.
Typically, semiconductor gauge are first considered for an application where low strain conditions or severe overload requirements are present. Essentially, in areas where a foil strain gauge is not suitable, or perhaps simply not ideal, a semiconductor strain gauge offers advantages with its high gauge factor. Semiconductor gauges can also be utilized where extreme space constraints exist, low loads exist, or where a high signal to noise ratio is required.
HITEC can utilize customer specified semiconductor strain gauges, or we can select and specify a strain gauge for you from one of the many manufacturers on the market. HITEC’s experience with all the major manufactures allows us to provide customers with the optimal solution in the challenging area of semiconductor strain gauge based transducers and stress analysis projects.
Examples of Semiconductor strain gauge based projects HITEC has been called upon include:
Multi-axis Robotic Quadraped
A leading human simulation and robotics company approached HITEC with a need to provide feedback from a quadraped’s legs to help in the study, and therefore improvement, in robotic motion actuation techniques. Various design studies were undertaken with the customer, from instrumenting an existing component to adding a separate transducer to the legs. The final approach settled on was a combination of the two which modified an existing component to provide better flexures to instrument for force feedback. Given the low loads, semiconductor strain gauges were employed in a full bridge configuration. To date, 100 robots have been instrumented with these transducers and have been utilized successfully at various Universities involved with Robotics study.
A leading government aerospace agency developed a requirement to measure forces in a humanoid robotic hand. Given the small in-situ space constraints for the gauge installation areas as well as forces/strains involved, semiconductor strain gauges were selected, a total of sixteen gauges per unit. The strain gauges make up what is called a phalange sensor which is composed of the phalanx bones that form each finger. The sensors ultimate purpose is to emulate a human astronaut’s hand and eventually are expected to be utilized to perform tasks that astronauts typically perform.
Trailer Axle Hub
A major over the road trailer axle suspension manufacturer was setting up manufacturing process equipment for axle assembly and needed a method of validating and verifying the process that ultimately determined axle bearing preload. The decision was made to instrument the component itself. Given the nature of the component, major modifications were not allowed as the validity of the data (as compared to production units) would be compromised. HITEC selected semiconductor strain gauges in a full bridge configuration as the solution given the low strain levels. This approach was a success and resulted in additional orders for the “tool” for other lines and assembly changes.
One of the more standard semiconductor sensors HITEC has been involved in. Semiconductor strain gauges were arranged in a simple bending arrangement on a cantilever beam. The sensor ultimately is utilized in a rheometer for physical testing for the rubber and plastics industries.
Prosthetic Knee Transducer
An innovative company in the prosthetic limb field approached HITEC with an existing design for force feedback on knee joints. Minimal design effort was required on HITEC’s part given the existing design, however our design engineers were called upon to help select proper semi-conductor strain gauges as well as devise the temperature compensation techniques required for production units.