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Page 1
Abstracts Submitted
Qiao, Feng
High-Frequency Vibration Driven Cutting
with Biological Inspiration for Minimally Invasive Surgery
Minimally Invasive Surgery has become more and more important in the medical application. It reduces the
operation danger and also the ache of patient. In this process the small surgical utensils will be inserted
through natural pathways to the operation site, or one mobile micro robot moves firstly through to make one
hole to the operation site for the following action.
For the minimally invasive surgery different working methods have been reported. Many use electrically driven
cutter to execute operation. Electrical energy brings ease, but although well protected, it is still one great
danger for the safety, especially for the operations at where nerves are densely located, for example in spinal
disc surgery. For this type of surgery, surgical utensils driven with high-frequency vibration are much more
safer. There are no sudden changes of effect at organism for vibrations with frequency below 40kHz.
The cutting behavior of leaf-cutting ants makes use of high-frequency vibration produced with an special
organ. When harvesting fresh vegetation, leaf-cutting ants anchor with their hind legs on the leaf edge and
rotate using the legs as a pivot. During cutting, ants produce high-frequency vibrations that led their
mandibles to vibrate at about 1 kHz, with an amplitude of about 1 µm, a process that mechanically facilitates
the cutting of the leaf tissue. This method is especially suited for cutting tender leaves, and ants have been
observed to reach a cutting speed of 0.22mm/s [1].
The work in this paper deals with transferring high-frequency vibration energy, or ultrasonic energy with
conductor to the operation site. Ultrasonic lithotriptor made of steel has been previously used for the removal
of ureteric stones [2]. But it will be difficult for solid conductor to transfer energy through bends with high
curvature. Fluid metal as the conductor for vibration was investigated.
Galinstan is one product of Geratherm [3]. It is one mixture of Gallium, Indium and Titan, and has a melting
point of -20°C. At normal body and room temperature it is in fluid state. It has the Density of 6,44g/cm⁄. And
with Echo-Pulse-Method the propagation velocity of longitudinal sound wave has been measured to amount
about 2950 m/s. Thus it has an acoustic impedance of about 18.9´10 kg/(m◊s), which fits well with the
acoustic impedance of vibrator made of Titan (acoustic impedance 18,7´10 kg/(m◊s)). And it has also low
absorption factor of 20cm/20dB. Furthermore this material is harmless to the health.
For energy transferring, fluid metal, Galinstan, was filled in Teflon-tube with inner diameter of 0.7mm. At
proximal end the tube was connected with vibrator. At distal end one small piston was stuck in the tube. The
Teflon-tube bounds the sound wave, and the vibration is transferred through Galinstan to drive the piston
reciprocating. The tube could be bent with high curvature. Still there was no great energy output loss at
piston. Two methods of energy coupling between Galinstan and vibrator and test results will also be
[1] J. Tautz, F. Roces and B. Hölldobler: Use of a Sound-Based Vibratome by Leaf-Cutting Ants; Science,
Vol 267, 6.January 1995, pp84-87.
[2] U. Stumpff: Die Erzeugung und Übertragung von Ultraschalldehnwellen hoher Energiedichte in flexiblen
Wellenleitern im 20 kHz-Bereich für therapeutische Anwendungen. Dissertation, 1978, RWTH Aachen.
[3] Geratherm GmbH Sicherheitsdatenblatt nach 93/112/EG, 1998, D-98716 Geschwenda
Biomedical: Biomedical
Department of Micro System Technology, Ilmenau Technical University
Session 2
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