Tactile tissue characterisation by piezoelectric systems

Abstract

For devices having non-linear contact, load plays a fundamental role. Variations in the characteristics of the load cause change in eigenfrequency and amplitude of the vibration. In most technical applications, this unwanted behaviour is cancelled by the use of control algorithms. However, multiple applications, like bond quality monitoring or chemical and pressure sensors, have found that the load may be characterised by interpreting the change in characteristics of a resonant vibrating device used as a sensor. Surgical resection of tumours is a very difficult task. After localising the tumour by the use of imaging techniques, the resection demands the surgeon to decide where and what to resect based on visual and tactile differentiation of tumour and healthy tissue. Exactness of this process could be enhanced if we can provide the surgeon with a device capable of evaluating mechanical characteristics of the tissue much more accurately than the surgeon himself can do. As the mechanical characteristics of tumour and healthy tissue differ but slightly, the task is to design a system with high sensitivity. Therefore, we have developed a resonant actuator-sensor that allows the differentiation among distinct media that have similar mechanical characteristics to tumour and healthy tissue using a piezoelectric bimorph. The design is based on the detection and evaluation of frequency shift and amplitude variation of the fundamental and higher harmonics using one layer for the resonant excitation of vibration and the other one as the sensing element.

A model of ionic polymer–metal composite actuators in underwater operations

“…Spatial monitoring using autonomous robots could greatly outperform the results that can be obtained by either fixed monitoring stations or sensors towed by a ship. On the other hand, probes that help to limit surgical invasion, for example using endoscopic tools, are of great interest to minimize the risk of side effects [36]. Based on these considerations, the behavior of IPMC actuators immersed in air, a synthetic fluid, deionized water, sea water, and human blood is shown in figure 17.…”

Other Surface-Acoustic-Wave Based Instruments

“…For the details, see Sect. 9.3. kHz resonators have also been applied to biological tissue [18,19]. The resonator touches the object of interest.…”

Magnetic resonance imaging-compatible tactile sensing device based on a piezoelectric array

“…These tools usually only contain one sensor, mounted at the tip or remotely, and can measure only a single point; 14,15 many are based on a vibrotactile sensing methodology. 16–18…”

“…These tools usually only contain one sensor, mounted at the tip or remotely, and can measure only a single point; 14,15 many are based on a vibrotactile sensing methodology. [16][17][18] Most of these forms of tool design are intended for manual operation, wherein the clinician operates the device by squeezing a handle or trigger (grasping tools/ forceps) or manipulates the end of the tool directly on to the tissue. For most, operation is intended to be similar to the use of standard MIS tools, therefore, they are useful when the desired general area of application is known and can be localised by endoscopic imaging.…”