3. Introduction
● Lumbar puncture (LP) is a
procedure that extracts
cerebrospinal fluid (CSF)
from the subarachnoid
space from the spinal space
in the lumbar region of the
lower back.
● The current problem is to
control the insertion
depth to protect injury
due to over penetration.
● This project is improves
the manual control to
automatic control in the
depth of insertion which
will decrease the
possibility of injury in
lumbar puncture.
4. Original Objectives
● Control the distance of insertion and the force
applied on the lumbar puncture needle.
● Automatic stop of the insertion to protect the
nerve system.
● Move back mechanism to avoid over
penetration due to the bounce of the dura
mater.
● Minimize the weight of the lumbar puncture
needle to better handle.
5. Objectives Achieved
● Emergency button to move the needle backwards
● Control the distance of insertion and the force
applied on the lumbar puncture needle.
● Automatic stop of the insertion to protect the
nerve system.
● Move back mechanism to avoid over
penetration due to the bounce of the dura
mater.
● Minimize the weight of the lumbar puncture
needle to better handle.
6. Design criteria
Requirement Value Unit
No. Of DOF 1 -
Force range 0-20 N
Response time 51 ms
Speed 0-10 mm/s
Overshoot distance 0-8 [3] mm
7. Design details
● Coaxial needle design made up of an inner and
outer needle.
● The inner needle experiences the cutting force
● The outer needle experiences the shear force
from surrounding tissues
8. Ft = Cutting
force
Fa = Actuator
force
Fs= Shear force
from
surrounding
tissues
Fh= Handling
force
9. Procedure Points
● The cutting force should change as the
inner needle goes through several tissues.
● Force sensor at the end of the hub of the
cutting needle reads the force changes
● Outer needle takes the shear force
● Force drops as the CSF area is reached
● Brake is activated.
● Tube is connected to the hub of the outer
needle to collect the CSF fluid when it
14. Summary of testing
Test Number of test made
Motor Test 5
Force sensor Test 4
Force drop Test 4
Final assembly test 6
15. Step Motor Test Result
● The stepper motor is tested on
its performance on
acceleration , velocity and
angular velocity.
● The relationship between
actual velocity and angular
velocity which is y = 0.314*x +
0.1163, where y is the angular
velocity in rad/s and x is the
actual velocity input in steps/s.
16. Force Sensor Test Result
● The benefits of the dead
band compensation are that
it can reduce the settling
time and lower the steady
state error.
● The calibration equation is y
= 0.1943*x, where x is the
sensor output and y is the
value in N.
17.
18. Final Assembly Test Result
(Styrofoam)
● The insertion automatically stops when it penetrates the
styrofoam plate. The overshoot distances are different for each
sample.
Sample A Sample B Sample C
19. Final Assembly Test Result
● The overshoot distance
should be with 8 mm. so
sample A and sample C
are accepted as
successful insertion. So
the successful rate is 75%
in the 6 tests.
● The setting of the
deadweight in the
programing code is too
large that decrease the
sensitivity of the force
sensor.
Overshoot distance of each sample
20. Societal and Economic Impacts
Social Economic
● —USA-400,000 lumbar
punctures per year
● —1/1000 injured every year
● —Reduced to 1/300,000
● —Health-adjusted life
expectancy
● —Reduces public spending
on health care
● —Increases disposal income
of patients
