Latest full-bridge sensors offer more advantages

VPG's Micro-Measurements division has expanded its product line of Transducer Class full-bridge strain gauges based on Advanced Sensors technology. Offering several advantages over bonding multiple, individual strain gages, the devices are now available with smaller, higher resistance patterns to serve a variety of bending and torque / shear applications. The strain gauge has been in use for many years and is the fundamental sensing element found in many types of precision force measuring transducers, including pressure, torque, load, and position. The Wheatstone bridge electrical circuit is most commonly used to sense strain gage resistance changes. This circuit requires four electrical resistance elements connected into a series / parallel configuration. One, two, or four strain gauges can serve as the four resistance elements, with precision resistors making up the partial configurations. The full-bridge circuit (with four active strain gages) provides for the highest measurement sensitivity and the best extraneous temperature cancellation. The S5056, S5020, S5046, and S5047 strain gauges offer improved grid-resistance tolerance and grid-to-grid temperature matching compared to traditional gages. Micro-Measurements offers a wide range of pattern configurations and resistance ranging from 350ohm to 20kohm. The addition of gold-plated solder pads improves lead wire attachment and solder-joint reliability, reducing the chances of solder pad oxidation prior to attaching the lead wires. Compared to bonding multiple individual strain gages, the full-bridge devices provide simplified, more precise alignment and reduced bonding operations. All four active arms of the Wheatstone bridge circuit are formed on a single carrier, allowing the entire bridge to be bonded at one time. All intrabridge connections are integrated into the pattern, thus eliminating intrabridge soldering. "Eliminating intrabridge wiring and soldering helps to reduce zero TC problems," said Ron Zukerman, Micro-Measurements Advanced Sensors manager of marketing and sales. "With no internal bridge wiring required, soldering is reduced to just four instrument wire connections, which greatly improves reliability. In addition, with all four arms of the Wheatstone bridge being manufactured simultaneously from a single piece of foil, grid-to-grid thermal characteristics are more closely matched, and thermal output is cancelled in the bridge circuit." The sensors are available in a variety of sizes, configurations, and mounting technologies. For the S5056, S5020, S5046, and S5047, the Advanced Sensors production line enables prototyping, one-piece, and high-volume manufacturing capabilities, says the company.