Vol.2, No.6, 435-438 (2009)
SciRes Copyright © 2009 Openly accessible at http://www.scirp.org/journal/JBISE/
Design and development of a new biomedical/open
surgical instrument
Zheng Li
University of Bridgeport, Bridgeport, USA
Email: zhengli@bridgeport.edu
Received 19 May 2009; revised 30 May 2009; accepted 1 June 2009.
This article introduces a new biomedical / open
surgical instrument to assist surgeon in apply-
ing surgical clips to patient’s body tissue and
blood vessel during surgical processes. The
new clip delivery system is designed to better
the clip’s distal advance through internal clip
channel, jaw guiding track, and all other transi-
tion areas to keep surgical clip from accidental
shooting out during clip’s distal move into jaws.
Currently the clip distal move in normal surgical
instrument is usually driven by compression
springs and some complains of clip accidental
drop-off were recorded in surgical procedures.
Because higher request of dimensional toler-
ance and better component surface quality are
needed in case the compression springs are
used as driven force, a little dimensional devia-
tion or less qualified part surface produced from
manufacturing processes will potentially cause
surgical clip device malfunction or misfiring of
the clips. It is clearly known that the jaws can
seriously sever or damage patient’s blood ves-
sel or body tissue if there is no clip inside the
jaws due to accidental clip drop-off, when sur-
geons close instrument handles. The improved
internal system design in this new open surgical
instrument can prevent clip from accidental
drop-off because of well guided and controlled
clip distal move through internal clip channel
and track. Besides the operational force to fully
form clip is lower than existing surgical clip de-
vices due to better mechanical advantage in this
new instrument design. In addition to the above,
manufacturing and product cost can be de-
creased since lower requirement of dimensional
tolerance and surface quality of instrumental
parts is allowed in this new surgical instrument
design. This new instrumental prototype is build
upon the analysis of computer aided modeling
and simulation to prove its good mechanical
advantage, feasible function, reliable perform-
ance. The preliminary results of instrument fir-
ing force from both computer aided modeling
and prototype testing are very close to each
other, and preliminary prototype testing shows
no accidental clip drop-off in this new biomedi-
cal / surgical clip instrument.
Keywords: Blood Vessel; Body Tissue; Ligation;
Computational Modeling; Mechanical Advantage
It is critical for surgeons to apply surgical clip instru-
ment to the severed organs, blood vessels and body tis-
sues to stop bleeding in surgical procedure [1,2,3]. The
surgical clip instrument jaws should be put around patent
blood vessel or body tissue and clips can be closed to
secure the vessel and tissue to prevent them from bleed-
ing when surgeon bring instrument handles together.
Next surgical clip will be automatically driven into in-
strument jaws through internal clip channel when sur-
geons release instrument handles.
The surgical devices to apply clips onto blood vessel
and body tissue have been developed for many years [4,
5,6]. It includes single clip and multiple clip applications
[7,8,9]. Next clip can be loaded into instrument after
firing each clip in single clip applications and multiple
clips can be sequentially applied to the vessel or tissue in
multiple clip applications. The surgical clip devices usu-
ally have two handles, a master body, a clip loading and
crimping assembly, clip driving mechanism and some
other functioning components such as clip pusher and
jaws. The improvement for better clip advancement and
lower cost instrument is continued to develop more reli-
able, better functional and cost-effective clip instruments
to support surgeons in their surgical processes.
Some complains were previously recorded from clinic
fields showing several incidents of accidental clip
shooting out from jaws while clip was driven into jaws
Z. Li / J. Biomedical Science and Engineering 2 (2009) 435-438
SciRes Copyright © 2009 http://www.scirp.org/journal/JBISE/
Openly accessible at
in clip instruments using compression springs as driving
force. These incidents showed that the closed jaws will
potentially sever or damage blood vessel or body tissue
if there is no clip in jaws. The accidental clip drop-off is
mainly caused by improper control of dimensional tol-
erance when manufacture the instrumental components.
The surgical instruments in which surgical clips were
driven by compression spring require higher dimensional
tolerance control and better surface quality during com-
ponent manufacturing and this will lead a low volume
and high cost instrumental production, otherwise the
clips will drop-off or shooting out if dimensional toler-
ance are too loose or clips will jam or not move by
spring force if dimensions are too tight.
This new instrument design has different clip delivery
system compared with current clip instruments. The dis-
tal movement of clip pusher driven by instrument han-
dles gradually advances clip from clip magazine,
through clip channel and transition area between clip
channel and jaws, and finally form clip after clip being
driven into guide track in jaws. The clip pusher returns
proximally to its original start position when surgeons
release instrument handles and then readily picks up next
clip. Since the internal clip delivery can be easily and
well controlled through simple lever-linkage driving
system in this new design, the accurate dimensional tol-
erance control and higher surface quality are not re-
quired during production and manufacturing processes
of instrumental components. This can lead cost-effective
machining process, increase production volume, and
reduce production cost. The preliminary prototype test-
ing also indicates that there is no accidental clip shooting
out in this new instrument design and operational force
to fully form clip is lower than current surgical clip in-
This new instrumental prototype testing has been
conducted on dogs including vascular occlusion, ligating
for tubular ducts, and applying surgical clip to animal
tissue. In vitro and in vivo studies were conducted to
investigate the clip holding force, degradation rate, and
tissue reactivity for clips of titanium material. The clips
were applied across excised canine cystic ducts by this
new instrument and both axial and transverse pull-off
forces have been recorded and measured. In the next
phase, the titanium clips were implanted subcutaneously
into the animals and the remaining strength within the
clips has been measured after 1, 3, 5, 7, 9, 11, 13, or 21
days. The preliminary results show that the clips applied
by this new surgical instrument function properly.
The preliminary testing results also indicated that
there is no clip shooting out in this surgical instrument
design and the operating force to fully form the clip is
between 3.16 lbf and 3.30 lbf which are lower than 4 lbf
in existing surgical instrument.
The prototype, instrument front and rear portion views
of this new surgical instrument are indicated in Figure
1-3. First the instrument will be put around patient blood
vessel or body tissue. When surgeons start and gradually
close instrument handles, clip driven by clip pusher ad-
vances distally from clip magazine through internal track
and channel into jaws and finally secured blood vessel or
body tissue. The instrument jaws can be open as sur-
geons release instrument handles, and clip pusher and
driving bar return to its original start positions. Com-
pared with current instrument that clip delivery is driven
by compression spring, the clip being loaded into jaws is
well guided and controlled in this new instrument design.
The driving bar linked to instrument handles at pivot
point moves distally to drive clip pusher that advances
clip steadily into jaws as surgeons gradually close surgi-
cal instrument handles. Such a stable clip linear motion
in this new design can be easily and well controlled by
surgeons to prevent clip from accidentally shooting out
from instrument. The preliminary prototype testing of
Figure 1. Prototype of new surgical instrument.
Figure 2. Front portion view of new surgical instrument.
Z. Li / J. Biomedical Science and Engineering 2 (2009) 435-438
SciRes Copyright © 2009 http://www.scirp.org/journal/JBISE/
Openly accessible at
Figure 3. Rear portion view of new surgical instrument.
Figure 4. Force analysis diagram in instrument.
this new design indicated its proper and reliable per-
formances with no clip shooting out and lower opera-
tional force than usual to form surgical clips.
Referring Figure 4, the energy balance and force equa-
tions in this new surgical instrument design can be de-
rived as follows.
Fload * Vlinear = T * ω (1)
Because torque T = Fpivot * R,
T * ω = Fpivot * R * ω = Fpivot * Vangular (2)
Fload * Vlinear = Fpivot * Vangular (3)
Fload = (Vangular / Vlinear ) * Fpivot = (VR) * F
pivot (4)
Referring the force diagram of this instrument handle
in Figure 4:
Ffinger * L = Fpivot * R (5)
The different Ffinger can be determined with different
combination of L and R. The computational simulation
can find the optimized values of L and R to reduce the
operational force to fully form clip. The computer aided
solution suggested L = 4.85 inch and R = 2.20 inch for
best instrument performance.
Based on Eq.5,
Ffinger * 4.85 = Fpivot * 2.20
Fpivot = 2.20 * Ffinger
Referring Eq.4,
Fload = (VR) * Fpivot = (VR) * 2.20 * Ffinger (6)
The velocity ratio of (Vangular / Vlinear) can be deter-
mined by computer aided simulation targeting optimized
instrument performance, and simulation results are
shown in Figure 5.
The mechanical advantage of this new instrument can
be found when surgical clip is fully formed:
Mechanical advantage = (VR) * 2.20 (7)
= (.04940 / .03548) * .20 = 3.063
This result shows that, if 20 lbf forces are required to
fully form the surgical clip, the operational force that
surgeon needed is 3.265 lbf that is lower than normal
spec of 4 lbf and this will benefit surgeons in their sur-
gical procedure. Also, both computational simulation
and prototype testing results are very close which verify
and prove the credibility of this new instrument design
and research methodology.
The prototype of this new surgical clip instrument has
been proved to have feasible function and better per-
formance based on instrumental functional study, com-
puter aided modeling and solution, and preliminary pro-
totype testing. This new instrument design has several
Figure 5. Linear and angular velocity vs. time phase in op-
erating the instrument.
Z. Li / J. Biomedical Science and Engineering 2 (2009) 435-438
SciRes Copyright © 2009 http://www.scirp.org/journal/JBISE/
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major advantages compared with some current surgical
clip devices including: the clip’s distal move can be
properly guided and controlled to prevent patient’s blood
vessel and body tissue from damage that caused by ac-
cidental clip shooting out during surgical processes, op-
erational force to form clip is lower than usual surgical
clip instruments, instrument production and product cost
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low surface quality of instrumental components are al-
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product cost.
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Openly accessible at
Ffinger – lbf, load on surgeon’s finger
T – inch-lbf, torque on pivot point of handle
Vlinear – inch per second, linear distal moving velocity of
instrument drive bar
Fload – lbf, force required to close jaws to form clip
L – inch, distance between handle pivot point and sur-
geon’s finger position (VR) – velocity ratio
R – inch, distance between handle pivot and linkage
Fpivot – lbf, load on linkage pivot
ω – degree per second, angular speed of handle at pivot