Tissue characterization using an acoustic wave tactile sensor array

Tactile perception of different types of tissue is important in order for surgeons to perform procedures correctly and safely. This is especially true in minimally invasive surgery (MIS) where the surgeon must be able to locate the target tissue without a direct line of sight or direct finger touch. In this study, tissue characterization using an acoustic wave tactile sensor array was investigated. This type of tactile sensor array can detect the acoustic impedance change of target materials. Abnormal tissues can have different Young's moduli and shear moduli caused by composition change compared to those of healthy tissues. This also leads to a difference in acoustic impedance which can be detected using our sensor array. The array was fabricated using a face-shear mode PMN-PT piezoelectric resonator which is highly sensitive to acoustic impedance load. Gelatin and water mixtures with weight concentration of 5 wt % - 30 wt % were prepared as tissue phantoms. The shear modulus of each phantom was measured using bulk face-shear mode crystal resonators, and it was found that shear modulus change from 120 kPa to 430 kPa resulted on 30 % electrical impedance shift from the resonator. Imaging display of elastic properties of prepared phantoms was also tested using the fabricated sensor array. The proposed tissue characterization technique is promising for the development of effective surgical procedures in minimally invasive surgery.