J. Biomedical Science and Engineering, 2011, 4, 119-121
doi:10.4236/jbise.2011.42017 Published Online February 2011 (http://www.SciRP.org/journal/jbise/
JBiSE
).
Published Online February 2011 in SciRes. http://www.scirp.org/journal/JBiSE
Computer aided modeling and analysis of a new biomedical
and surgical instrument
Zheng L i
University of Bridgeport, Bridgeport, USA.
Received 12 November 2010; revised 15 November 2010; accepted 19 November 2010.
ABSTRACT
This paper describes the recent research and devel-
opment of an endo surgical/biomedical instrument in
surgical suture applications for minimally invasive
therapy procedure. The newly developed instruments
can not only protect the wound during the surgical
procedure but also actively help the healing process.
The new mechanism design of the surgical instrument
aids in better ergonomic design, reliable functionality,
and continuous cost reduction in product manufac-
turing. 3-D modeling technique, func tionality an alysis,
kinematical simulation and computer aided solution
have been applied to the instrument design, devel-
opment and future improvement to meet the specific
requirements of minimally invasive surgery proce-
dure. The improved new endo surgical/biomedical
instrument can prevent patient’s vessels and tissues
from being damaging because the distal move of clips
are well controlled without clip drop-off incident.
Plus the operational force to form the clip is lower
than regular surgical/biomedical instruments due to
this special new mechanism design. In addition to the
above, the manufacturing and product cost can be
decreased because the dimensional tolerance of com-
ponents, such as clip channel and jaw guide track,
can be loose due to this new instrument design. The
prototypes of this new endo surgical/biomedical in-
strument design are analyzed through computer
aided modeling and simulation, in order to prove its
feasible functionality, reliable performance, and me-
chanical advantage. All these improved features have
also been tested and verified through the prototypes.
Keywords: Hemostasis; Endoscopic Device;
Computational Simulation; 3-D Modeling; Mechanical
Advantage
1. INTRODUCTION
The newly developed technologies have directed mini-
mally invasive surgeries [1]. The positive and feasible
changes in surgical instruments have led to the new de-
velopment of surgical techniques [2] and [3]. The bio-
medical and surgical instrument market is always ad-
justed and controlled for its functionality, performance,
feasibility, quality, safety, and manufacturing cost. The
surgical instrument market is very competitive, price
sensitive and depicted by advanced technologies [4] and
[5]. Biomedical and surgical instrument is technology
based product and normally advanced techniques are
especially required to develop special technology to
compete the products in today’s challenging market [6].
The applications include the closure of tissue defects,
perforations, and anastomotic leakage in the esophagus
and stomach. The endo surgical instrument has also been
used to prevent post-polypectomy bleeding, placement
of enteral feeding tubes. The recent studies show the
versatility of endo surgical clips in therapeutic and en-
doscopic applications.
This endo surgical instrument is the innovative product
that will allow for greater ease of use for surgeons and
help to improve patient outcomes. Based on the field and
clinical feedback, the new technology that simultaneously
opens and aligns the jaws has been implemented, allow-
ing well controlled surgical clip feeding and closure. This
new surgical instrument design can provide more con-
sistent and reliable mechanism to protect the clip from
external and unanticipated disturbance while the surgical
clip sits in the jaw track.
Endo surgical instrument has been widely used in
hemostasis during endoscopy of the upper and lower
gastrointestinal tract in which the bleeding lesions can be
successfully clipped. The alternatives to endoscopic
clipping of peptic ulcers are thermal therapy (such as
electrocautery to burn the vessel causing the bleeding),
or injection of epinephrine to constrict the blood vessel.
Comparative studies between endo surgical clips and
thermal therapy verify that endo surgical clips cause less
trauma to the mucosa around the ulcer than electrocau-
tery.

J. Li et al. / J. Biomedical Science and Engineering 4 (2011) 119-121 120
2. ANALYSIS OF ENDO SURGICAL
INSTRUMENT
The operation procedure of endoclip instrument is de-
scribed as follows. An endo surgical clip is loaded onto
an endo surgical instrument and retracted into a protec-
tive sheath. The instrument is inserted through the open
channel of an endoscope. Forcing the sheath backwards
through the handle can drive the clip from the sheath.
Pulling the clip back can open the prongs. When instru-
ment jaw tips fully open, the distance between the clip
prongs reaches the maximum. The orientation of the
endo surgical clip prongs can be controlled by turning
the instrument handle clockwise. The surgical clip can
be closed by fully pull the clip proximally. In hemostasis
application, the endo surgical clip is used to compress
and clamp a bleeding vessel. If the vessel is clamped
properly, the ligation should be permanent. Compared
with the thermal and injection ligation, the endo surgical
clip is the direct mechanical method that can reduce the
injury to the near tissue. Endo surgical clips have been
positively applied in the control of GI bleeding from
multiple sources including peptic and stomal ulcers, le-
sions, gastric tumors, colonic diverticula, solitary rectal
ulcers, and post-sphincterotomy bleeding.
The Figure 1 shows new endo surgical instrument,
Figure 2 indicates the cross-section of new endo surgi-
cal instrument, and Figure 3 displays the jaw mecha-
nism section.
Figure 1. New endo surgical instrument.
Figure 2. Cross-section of new endo surgical instrument.
Figure 3. New endo surgical instrument jaw mechanism.
3. COMPUTER AIDED MODELING AND
SIMULATION
load linear
N*V M*


(1)
pivotpivot angular
M *N*r*N*V



 (2)



loadangular linearpivotpivot
N=VV*N =Vr*N (3)
The computer aided modeling and optimal simulation
of S and r combination can help to reduce the opera-
tional force and determine the minimum instrumental
handle force Ffinger that surgeon needed to operate the
surgical instrument. The computer aided solution indi-
cated that S = 4.90 inch and r = 2.15 inch for best in-
strument performance.
Based on equation (3),
490215
finger pivot
N*.N*.
Referring equation (4),


228
load pivotfinger
NVr*NVr* .*N ( 4)
The velocity ratio of


angular linear
VV can be found
through computer aided modeling and simulation to de-
termine the optimal instrument function. The computa-
tional solution is indicated in Figure 5.
Then the mechanical advantage of this new surgical
instrument is as follows:


228
04940035482 283 175
M
echanical ad vant ageVR*.
..*. .


(5)
This result indicated that the surgeons only need 3.149
lbf closure forces when 20 lbf forces are required to fully
form the surgical clip. This is lower than normal spec of
4 lbf and it will benefit surgeons in their surgical opera-
tion and procedure. Furthermore, the computer aided
modeling and simulation results are very close to the
prototype testing results that verify the credibility and
reliability of this new endo surgical and biomedical in-
strument. The prototype units have been sent to the sur-
C
opyright © 2011 SciRes. JBISE

J. Li et al. / J. Biomedical Science and Engineering 4 (2011) 119-121 121
JBISE
Figure 4. Linear and angular velocity vs. time in instrument
operation.
geons and clinic fields for more evaluations and feed-
backs. Future modification will be anticipated to further
improve instrumental function and reduce the unit cost.
4. CONCLUSION
This paper introduces a new endo surgical instrument
design using 3D computer modeling and simulation. 3D
modeling and computer aided simulation can benefit
geometrical, kinematical and dynamical analysis in con-
ceptual and feasible design of biomedical and surgical
instruments. The geometric, kinematical, dynamical and
visual limitations of the surgical instruments are ana-
lyzed to assist the surgeon in surgical procedure. The
kinematics of precision instrumental mechanism design
can be simulated and modeled as either an open or
closed-loop joint chain with some rigid bodies connected
to each other in a series format, driven by actuated
mechanism. The analysis of kinematical structure in
mechanism can provide a systematic and general ap-
proach to determine and calculate mechanism motion
functionality. The kinematical and dynamic simulation
of these multiple link system permits conceptual verifi-
cation and feasible studies in the design and develop-
ment stage. The computer aided simulation and proto-
type testing have shown the feasible and reliable func-
tion of this new endo biomedical and surgical instru-
ment.
REFERENCES
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[2] Charabaty-Pishvaian, A. and Al-Kawas, F. (2004) Endo-
scopic treatment t of duodenal perforation using a clip-
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doi:10.1097/01.SMJ.0000091031.77846.B6
[3] Dhalla, S.S. (2004) Endoscopic repair of a colonic per-
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Nomenclature
M: inch-lbf, torque on pivot point of trigger
Nload: lbf, force required to close the jaws
S: inch, distance between trigger pivot center and surgeon’s finger position
Npivot: lbf, normal force on linkage pivot
ω: degree per second, angular speed of trigger at pivot center
Nfinger: lbf, force on surgeon’s finger
Vlinear: inch per second, distal linear moving speed of instrument drive bar
(Vr): velocity ratio
r: inch, center distance between trigger pivot and linkage pivot
Vangular: inch per second, angular tangential speed at trigger pivot center