Chemical and Biomolecular Engineering, Department of


Date of this Version


Document Type



ACS Appl. Mater. Interfaces 2014, 6, 16368−16374


Open Access licensed.


Apart from texture, the human finger can sense palpation. The detection of an imbedded structure is a fine balance between the relative stiffness of the matrix, the object, and the device. If the device is too soft, its high responsiveness will limit the depth to which the imbedded structure can be detected. The sensation of palpation is an effective procedure for a physician to examine irregularities. In a clinical breast examination (CBE), by pressing over 1 cm2 area, at a contact pressure in the 70−90 kPa range, the

physician feels cancerous lumps that are 8- to 18-fold stiffer than surrounding tissue. Early detection of a lump in the 5−10 mm range leads to an excellent prognosis. We describe a thin-film tactile device that emulates human touch to quantify CBE by imaging the size and shape of 5−10 mm objects at 20 mm depth in a breast model using ~80 kPa pressure. The linear response of the device allows quantification where the greyscale corresponds to the relative local stiffness. The (background) signal from