Biomedical Engineering Reference
In-Depth Information
the right column are consistent with the experimental data. However, implementation of
this algorithm may produce gray areas in the middle of the image in the absence of any
lump. To rectify this problem, an enhanced algorithm is under development.
8.4 Summary and Conclusions
An MIS grasper capable of measuring the softness of the grasped objects is reported in the
first part of this chapter. A feedback system is designed and incorporated into the sensor
array assembly on the grasper jaws in order to transmit tactile signals from the grasper
to the signal processing system. For the next step, we developed a signal processing
and display system which enabled tactile data, such as tissue softness gathered from the
tissue/grasper interface, to be viewed on a computer monitor, in the form of a graphical
representation, and the results were discussed.
In the next part of this chapter, a system for characterizing and rendering hidden lumps
in soft bulk objects is presented. The proposed system comprises an endoscopic grasper
equipped with array(s) of tactile sensors, a signal processing unit, a graphical rendering
algorithm, and a graphical display. This setting potentially could be used for nodule
detection in laparoscopic surgery.
Initially the required information was collected from the grasped object by using a
multifunctional tactile sensor that had already been developed. A unit of the utilized
sensor is capable of measuring the applied contact force as well as the softness of the
grasped object. An array of the sensor used in this study is also capable of reporting the
location and size of the lump. The output voltages of the sensing elements are buffered,
digitized, filtered, and transmitted to a computer. Then, through a rendering algorithm
developed in the LabVIEW environment, the tactile data were transformed to grayscale
images and were displayed on a monitor.
The experiments on the prototype graspers were conducted and the data were graph-
ically rendered on a display. Hard objects were inserted into pre-determined positions
in elastomeric material and were held by the grasper and the calculated images were
compared with known images.
Graphical rendering of localized objects is a feasible technique with great potential
for use in MIS. Using this method, a part of the lost tactile information available from
palpation can be restored. This capability is useful not only for MIS, but also for MIS
robotic surgery and robotic surgery in general. This research also paves the way for
other anatomical applications elsewhere, such as beating arteries that could potentially be
detected and graphically rendered.
References
1. Narayanan, N.B., Bonakdar, A., Dargahi, J. et al . (2006) Design and analysis of a micromachined piezo-
electric sensor for measuring the viscoelastic properties of tissues in minimally invasive surgery. Smart
Materials and Structures , 15 , 1684 - 1690.
2. Dargahi, J., Najarian, S., and Zheng, X.Z. (2005) Measurements and modeling of compliance using novel
multi-sensor endoscopic grasper. Sensors and Materials , 17 , 7 - 20.
3. Dargahi, J. (2002) An endoscopic and robotic tooth-like compliance and roughness tactile sensor. Journal
of Mechanical Engineering Design (ASME) , 124 , 576 - 582.
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