US Patent 8044472 - Graphene pressure sensor

http://www.freepatentsonline.com/8044472.html

The application of stress to plural layers of graphene alters the semiconductor bandgap which changes the conductivity of the graphene layers. This patent from Kulite Semiconductor Products teaches using this property to construct a graphene-based pressure sensor. Claim 1 reads:

1. A transducer comprising:

a substrate a plurality of graphene semiconductive structures located entirely on a surface of the substrate, each of the graphene semiconductive structures being supported along its entire length by the substrate, wherein an electrical property of the graphene semiconductive structures changes with an applied force;

one or more metal pads securing at least one of the graphene semiconductive structures to the substrate; and

a circuit coupled to at least some of the graphene semiconductive structures to provide an output responsive to the change in the electrical property, the output being indicative of the applied force.

US Patent 7312096 - Nanotube wheatstone bridge sensor

http://www.freepatentsonline.com/7312096.html

This patent from Kulite Semiconductor Products teaches a method of forming a pressure sensor using nanotubes in a Wheatstone bridge configuration. Claim 1 reads:


1. A method of forming a pressure transducer comprising: providing a substrate; disposing a plurality of nanotube structures on a surface of said substrate, said plurality of nanotube structures having varying resistance values such that each of said plurality of nanotube structures corresponds to one of a conductive nanotube structure having a relatively low resistivity, and a semiconductive nanotube structure having a relatively high resistivity, and wherein at least one electrical property of said semiconductive nanotube structures changes with an applied force; selectively connecting at least some of said relatively high resistivity semiconductive nanotube structures to one another using at least some of said relatively low resistivity conductive nanotube structures to form a bridge circuit having a plurality of force sensitive bridge elements; wherein application of a force to said substrate causes a change in current through said bridge circuit according to the applied force.