Engineers and technicians often have a difficult time measuring contact and loads that components see during operation. To help, Sensor Products Inc., East Hanover, N.J., have packaged its pressure-sensitive film into Pressure Points. These small (0.3 to 1-in.-diameter) thin dots carry a pressure-activated adhesive on one side, which lets users place them in almost any hard-to-reach space. The sensor dot permanently and instantaneously changes color when force is applied. Color intensity is proportional to the force, giving users a way to tell magnitude and spatial distribution of forces. Comparing the color to a calibration chart is much like interpreting Litmus paper and lets users determine the applied forces.

Pressure Points come in a variety of pressure ranges, letting users measure anywhere between 28 and 18,500 psi with spatial resolutions ranging from 5 to15 microns and error rates of 10%. Scanning the pressure-sensitive dots with an optical measuring system can pinpoint the force with 2% error rates. The dots work in temperatures from 41 to 91F, relative humidity of 20 to 90%, and have a two-year shelf life.