M. E. H. Eltaib

Tactile sensing technology for minimal access surgery-a review

Abstract Minimal access surgery (MAS), also known as keyhole surgery, offers many advantages over the more traditional open surgery. However, it possesses one very significant drawback––the loss, by the surgeon, of the “sense of feel” that is used routinely in open surgery to explore tissue and organs within the operative site. Because of this, important properties such as tissue compliance, viscosity and surface texture, which give indications regarding the health of the tissue, cannot easily be assessed. Restoring this tactile capability to MAS surgeons by artificial means would bring immense benefits in patient welfare and safety. Artificial tactile sensing systems for MAS are reviewed. The technology is addressed from different viewpoints including those of the basic transduction of tactile data (tactile sensing), the computer processing of the transduced data to obtain useful information (tactile data processing) and the display to the surgeon of this information (tactile display). Applications of tactile sensing in MAS, both to mediate the manipulation of organs and to assess the condition of tissue, are reviewed. Some attempts to add tactile feedback to laparoscopic surgery simulation systems for MAS surgeon training are also described.

Micromachined Tactile Sensor for Soft-Tissue Compliance Detection

Compliance detection becomes very essential in minimally invasive surgery (MIS). It can help in detection of cancerous lumps and/or for deciding on tissue healthiness. In this paper, a micromachined piezoresistive tactile sensor, with two serpentine springs and 500-μm cubic mesas, has been designed for detecting the compliance of soft tissue independent of the applied distance between the sensor and the tissue. The measuring range of the sensor is chosen to be associated with the soft-tissue properties. The sensor parameters are optimized to give high sensitivity and linearity of the sensor output. The design is simulated using ANSYS for checking the sensor performance. Then, the sensor is fabricated and tested by three types of specimens, namely, specimen chips with known stiffness, silicone rubber specimens, and chicken organ specimens (leg and heart). For the specimen chips and silicone rubber specimens, the sensor distinguished between different stiffnesses independent of the applied displacement in the range of 50-200 μm. The sensor measured Youngs modulus up to 808 kPa with an average error of ±7.25%. For the chicken leg and heart, the sensor distinguished between them under the applied displacement from 100 to 200 μm, and they were calculated as 12 ±1 kPa and 81 ±8 kPa, respectively.

A Tactile Sensor for Minimal Access Surgery Applications

Abstract Touch sensing during new surgical techniques, such as laparoscopy and those involving robotic manipulators, is a challenge. In these techniques, tissue is remotely manipulated using instruments, which do not possess a sense of touch. Important properties such as tissue compliance, which give indications regarding the health of the tissue, can not be accessed. A tactile system for tissue assessment is described. It comprises a tactile sensor attached to the end of a sinusoidally vibrating rod. When the sensor indents the tissue a sinusoidal motion is transmitted to the tissue. The output of the sensor is the contact force between the tissue and the rod tip. This is used to identify the dynamic properties of the tissue. The design and implementation of the tactile sensor are described. Simple experiments involving simulated tissue have been undertaken and the results of these are reported.

Ambient vibrations piezoelectric harvester array with discrete multiple low frequencies

This work presents an approach to enhance kinetic energy harvesting from low multi-frequency discrete ambient vibrations. It is based on an array of three piezoelectric harvesters each with a certain resonant frequency that is triggered at a specific frequency in the vibration environment. The harvesters used in this work are of commercially available cantilever beam type. Their resonant frequencies are experimentally estimated. They are compared with the theoretical values from the model and good agreements are found. During operation, each harvester is modeled as a voltage source with a resistance and a capacitance load (i.e. RC circuit). The proposed approach discretely broadens the frequency band of power harvesting process and makes it more efficient and more suitable for practical implementations.