The High-Temperature FlexiForce flexible force sensor

The High-Temperature FlexiForce flexible force sensor

The company behind the High-Temperature FlexiForce flexible piezoresistive force sensors, Tekscan, was founded in 1987 to produce matrix, or array, sensors that are widely used in medical and dental applications, such as dental occlusal analysis. The sensors tend to be used in fairly low quantities, and are often highly customized for their end applications. But about 10 years ago, the company saw they could apply their technology in a new way to create flexible sensors in higher volumes and began their FlexiForce group.

The initial FlexiForce sensors were capable of operating at temperature up to about 140F. While this could serve in several markets, the company was approached around 2005 with a request for sensors that could withstand even higher operating temperatures. The company, which had been expanding and putting new investment into R&D and expanding its manufacturing capabilities, did some market research and determined that a flexible force sensor with high-temperature capability would find acceptance in many new area, including automotive, military, and industrial sensing.

In 2007, an team of engineers, manufacturing experts, and researchers headed by Thomas Papakostas, then vice president of research and development and now vice president of technology for the whole company, began to experiment with new materials. The polyester material previously used as the basis for the flexible sensors was incapable of withstanding high heat, so it was replaced with Kapton, a polyimide film developed by DuPont that remains stable at temperatures to about 750°F, and widely used for flexible PCBs.

But the key technology of the sensor was in the printed conductive and resistive ink and the adhesives used. Reformulating these screen-printable materials required experimentation, and the team began an iterative process which resulted, in late 2008, in suitable material that could be released for manufacturing. So in February 2009, the company introduced the High-Temperature FlexiForce sensors, which were shown to operate at temperatures as high as 400°F.

Since the introduction, the sensors have found ready acceptance in many academic circles, and are being designed into a wide range of prototypes for military, automotive, and industrial applications. (NDAs prevent the company from providing more details on the sensor’s uses, but end products using the sensor should be available in the near future.) And the technologies developed for the High-Temperature FlexiForce have been moved into the matrix sensor lines as well to provide them with improved capabilities.

Richard Comerford