Patent number 7,278,327 - “Film Based Position and Pressure Sensor” discloses an innovative sensor apparatus that offers the ability to simultaneously measure the actual position and magnitude of an applied force over a substantially continuous range using a minimal number of electrical interconnections. The apparatus is realized by two sensor elements that exhibit a decreasing width over the length of each sensor element and are arranged overlapping each other in a substantially complementary orientation to one another with respect to the width so that the point of the narrowest width of the first sensor element overlaps the point of the widest width of the second sensor element. Pressure applied to the sensor apparatus causes each sensor element to generate an electrical signal that is proportional to both the applied pressure and the surface area at the location of the applied pressure. As a result of the complementary orientation and overlapping of these sensor elements, the first and second sensor elements generate an asymmetric pair of signals that uniquely define the applied pressure by position and magnitude.
This invented pressure and position sensing apparatus is useful in robotics, biometric applications, and the like. One exemplary use in the area of biometrics is applied to the personalized handgun, being developed at NJIT for the Personalized Weapon Technology Program funded by the National Institute for Justice, US State Department and the US Army, for obtaining the applied force and size of the user's hand when gripping a firearm. The ultimate goal of this on-going program is to develop a handgun that uses dynamic grip recognition to instantly and reliably recognize one or more pre-programmed authorized users of each individual handgun as well as record all firing activities. The current version of the gun uses several technologies developed by Professor Chang including an embedded DSP (Figure 1) along with piezoelectric sensors (Figure 2) that are designed to provide high bandwidth, low power, low form factor, fast data processing and decision generation. These latter improvements are embodied in patent application13/043,035 – “System and Method for Weapon Discharge Inhibition”.
Figure 1 Handgun with embedded DSP.
Figure 2 Piezoelectric disk and film sensors.