All-electrical indentation shear modulus and elastic modulus measurement using a piezoelectric cantilever with a tip

Journal of Applied Physics, 101(5): pp. 054510-1 - 054510-10.We have investigated an all-electrical indentation shear modulus and elastic modulus measurement technique using piezoelectric cantilever sensors with a tip for potential in vivo applications. A piezoelectric cantilever with a tip was capable of carrying out compression, shear, indentation, and indentation shear tests, where compression and shear tests refer to those where the sample is not confined by a container and the contact area of the cantilever is the same as or larger than the sample surface area and the indentation and indentation shear tests are those where the contact area of the cantilever is smaller than the sample surface area. Because the cantilever could measure both the elastic modulus and the shear modulus, Poisson’s ratio of a sample could be determined from the ratio of the shear modulus to the elastic modulus with no presumption. We showed that the experimental elastic moduli and shear moduli obtained from the indentation and indentation shear tests agree with those obtained from the compression and shear tests. Furthermore, we showed that the same elastic moduli and the same shear moduli could be obtained either by using the displacement measurements or by the induced voltage measurements across the sensing piezoelectric layer. With a model tissue consisting of modeling clay embedded in gelatin, we demonstrated that the indentation compression and indentation shear tests could produce two-dimensional elastic and shear moduli maps or images that accurately showed the size and location of the modeling clay inclusion

Soft tissue elastic modulus measurement and tumor detection using piezoelectric fingers

2005 MRS Fall Meeting, 898, pp. 1-6.We have investigated probing breast tumor in a lumpectomy sample using a newly developed piezoelectric finger (PEF). PEF is a piezoelectric cantilever that consists of a top driving piezoelectric lead zirconate titanate (PZT) layer and a bottom sensing PZT layer sandwiched to a middle stainless steel layer. A PEF can both apply a force and detect the corresponding displacement in one single device by simple electrical means. Applying an electric field to the driving PZT layer causes the PEF to bend which in turn causes a measurable induced voltage across the sensing PZT layer that is proportional to the deflection of the PEF’s tip. Earlier studies have demonstrated that with the appropriate tip geometry, the PEF could accurately measure the elastic and shear moduli of a soft material. It could also differentiate and locate hard inclusions embedded in a soft matrix by the contrast of elastic moduli. In this study, we applied the PEF to probe a lumpectomy sample and located the tumor inside the sample using the spatial contrast of elastic moduli

Breast tumor detection and differentiation using piezoelectric fingers

Poster presented at Biomedical Technology Showcase 2006, Philadelphia, PA. Retrieved 18 Aug 2006 from http://www.biomed.drexel.edu/new04/Content/Biomed_Tech_Showcase/Poster_Presentations/W.Y.Shih_1.pdf.A piezoelectric finger (PEF) is a piezoelectric cantilever consisting of a driving and a sensing piezoelectric layer such as lead zirconate titanate (PZT) bonded to nonpiezoelectric layer, e.g., stainless steel. With the dual electrode design, a PEF can both apply a force and detect the resultant displacement with one single device. We have demonstrated that a PEF can measure both the elastic and shear moduli of tissues. Furthermore, we can locate and determine the size of a tumor non-invasively. By comparing the shear and elastic moduli of a tumor, we have the potential to differentiate malignant tumors from benign ones non-invasively. This unique ability of PEF stands to greatly aid tumor malignancy test accuracy