University of California

Georg Fantner

Paul K Hansma

Johannes H Kindt

Douglas J Rehn

Patricia J Turner

Methods and instruments for assessing bone, for example fracture risk, in a subject in which a test probe is inserted through the skin of the subject so that the test probe contacts the subject's bone and the resistance of the test bone to microscopic fracture by the test probe is determined. Macroscopic bone fracture risk is assessed by measuring the resistance of the bone to microscopic fractures caused by the test probe. The microscopic fractures are so small that they pose negligible health risks. The instrument may also be useful in characterizing other materials, especially if it is necessary to penetrate a layer to get to the material to be characterized.

Methods and instruments for assessing bone fracture risk

A scanner for probe microscopy that avoids low resonance frequencies and accounts better for piezo nonlinearities. The x, y and z axes of a linear stack scanner are partially decoupled from each other while maintaining all mechanical joints stiff in the direction of actuation. The scanning probe microscope comprises a probe, a housing, at least two actuators, each coupled to the housing, and a support coupled to the housing and to at least a first of the actuators at a position spaced from the point at which the actuator is coupled to the housing. The support constrains the motion of the first actuator along a first axis while permitting translation along a second axis. The actuators are preferably orthogonally arranged linear stacks of flat piezos, preferably in push-pull configuration. The support can take different forms in different embodiments of the invention. In a particular embodiment, the scanner is a 2D scanner having a support frame with x and y axes, and a member for supporting an object to be moved such as a sample for a probe, the scanner comprising a flexure and flexure coupled cross-conformed piezos arranged along x and y axes. Expansion of the piezos is measured by at least two strain gauges disposed to measure the differential motion of at least two opposed actuators. The strain gauges are preferably arranged to compensate for ambient temperature changes, and preferably two or more strain gauges of identical type are disposed on each actuator to magnify the strain signal.

Growing community of inventors

Santa Barbara, CA, United States of America

Georg Fantner