1. Capacitive Touch Sensor for
Foot Drop Paralysis Stimulator
Apivan Trungtrakul, Jirawat Jitprasutwit, Ratikorn Chaivattanatham
Advisor: Zeng Lertmanorat, Ph.D.
THAILAND, Mahidol University
iCAN 2011 Beijing China

2. Foot drop
@Faculty of Physical Therapy, Mahidol University

3. Cause of foot drop
Stroke
20% of survivors
They have foot drop.
Every year
15 million people suffer a stroke
5 million are left permanently disable
1 million Foot Drop per year

4. In Thailand
At less 400,000 Foot Drop

5. Treatments
• Tendon transfer (surgery)
• Ankle foot orthotic (joint support)
Tendon transfer Ankle foot orthotic

6. Electrotherapy:
Foot drop stimulator (FDS)
Sensor part
Control part
Electrical stimulator part
Nerve & Muscle
Contraction!!!

7. FDS in commercial
Force sensor Tilt sensor
Odstock Bioness L300 WalkAide XFT Electronic
Europe USA USA China
1,700 $ 6,500 $ 4,495 $ 1,380 $

8. Our sensor

9. Capacitive technique

10. Simple calculation

11. Sensor benchmark
Tilt sensor Force sensor Cap. sensor
Power consumption
Durability
Cost
Reliability
Extra electronic circuit
SCORE -1 -1 3

12. FDS system & accessory
Controller Capacitive
& sensor
stimulator
Set parameter via software
Electrode
FDS system

13. Commercial FDS
WalkUp FDS
1 adjustable knob
2 interface buttons
3 stimulation modes
300 – 400 USD (Thailand only)

14. Clinical Trial

15. Summary
New Sensing Technique
Capacitive touch sensor
Low Power Consumption
2.75 nA
High durability
PCB-based Sensor