University of Massachusetts

Sharavanan Balasubramaniam

Ramaswamy Nagarajan

Joey L Mead

Julie Chen

Shivshankar Sivasubramanian

Mario J Cazeca

Jungrae Park

Wireless strain and displacement sensors wirelessly monitor structural health and integrity, and are made by printing inductor-interdigital capacitor sensing circuits on a variety of substrates, including ceramic substrates, with thermally processable conductive inks. Sensors of the invention can be employed to detect strain and displacement of civil structures, such as bridges and buildings. The sensors include sensing elements that are mounted or printed on stiff, inflexible substrates, which prevent the sensing elements from bending, stretching, or otherwise warping when the sensor is strained. An interlayer between the sensing elements allows the sensing elements to move with respect to each other during application of strain. Thus, strain causes the sensing elements to move but not to deform, causing changes in sensor resonance that can be detected through wireless radio-frequency interrogation. Because the sensing elements do not change shape when under strain, the sensor can undergo millions of measurement cycles before breaking.

Wireless passive radio-frequency strain and displacement sensors

Metal flakes, an organic metal precursor, an organic solvent and either no binder, or a volatile or a thermally decomposable binder are combined to form a paste. The paste is deposited in a circuit pattern on a substrate and the circuit pattern is cured. While curing, the organic metal precursor decomposes to leave an electrically conductive path, and the printed circuit is thus formed. A precursor to an electrically conductive circuit material includes an organic metal precursor, metal microparticles, and an organic solvent. The method can be employed to form printed circuits, for a variety of electrical, electronic and sensing application, such as crack detection in ceramic, plastics, concrete, wood, fabric, leather, rubber or paper and composite materials.

Conductive formulations for use in electrical, electronic and RF applications

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Lowell, MA, United States of America

Sharavanan Balasubramaniam