Patent ID: 8544337

Claim:
An impact sensor, comprising: a chromic device having a first conductor, a second conductor, and a chromic material sandwiched between and operatively connected to the first conductor and the second conductor; a piezoelectric transducer having a first conductor, a second conductor, and a piezoelectric material sandwiched between and operatively connected to the first conductor and the second conductor; a first electrical connection electrically connecting the first conductor of the chromic device and the first conductor of the piezoelectric transducer; and a second electrical connection electrically connecting the second conductor of the chromic device and the second conductor of the piezoelectric transducer; wherein the chromic material changes from a first color state to a second color state in response to electric power generated by the piezoelectric transducer when exposed to a given level of impact force, wherein the chromic material is bistable so that the chromic material remains in the second color state for at least many minutes, wherein the chromic material is an electrochromic material comprising a viologen, and wherein the viologen changes through a color gradient of light transmission states from the first color state to the second color state; wherein at least a portion of at least one of the first and second conductors of the chromic device is substantially transparent so that the electrochromic material is visible through the substantially transparent portion; a printed color gradient key mounted near the chromic device, wherein the printed color gradient key includes: a photographic representation of two or more of the light transmission states; and indicia setting forth an impact force corresponding to each of the two or more light transmission states.