Force sensing ink, method of making same and improved force sensor

Abstract

An improved carbon-free force sensitive ink for a force sensor. The ink when deposited and dried can function at temperatures of up to 350.degree. F. and pressures of up to 10,000 psi. The preferred ink includes a thermoplastic polyimide binder, conductive particles, intrinsically semi-conductive particles, and dielectric particles, all of an average particle size of 1.0 micron or less. The preferred semi-conductive particles are molybdenum disulfide, ferric and ferrous oxide particles. The preferred conductive particles are conductive metal oxide compounds that deviate from stoichiometry based on an oxygen value of two, such as conductive tin oxide, Fe.sub.3 O.sub.4 iron oxide, and mixtures of them. The preferred dielectric particles are silica. The binder is present in an amount of 20 to 80% by volume. The sensor and a method of making the sensor are also disclosed.

Dependencies are inferred from the claim text.