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Fabrication and Design Considerations for Microfluidics-based Tactile Sensors for
Prosthetic Hand
Shehreen DhedaFaculty Mentor: Abraham P. Lee, PhD
Graduate Mentor: Jeffrey S. FisherDepartment of Biomedical Engineering,
University of California, IrvineAugust 31, 2006
Inter-Micro/Nano Summer Undergraduate Research Experience (IM-SURE)
Outline:
Biological mechanoreceptors of the human hand
Our synthetic tactile sensor design Device manufacturing and characterization
techniques and their outcomes Conclusions Acknowledgements
Biological Mechanoreceptors of the Human Hand
Kandel, E. The Principles of Neural Sciences, 2000
Slowly Adapting(SA(SA
) ) afferen
ts
Rapidly Adapting (RA) (RA) afferent
s
(SA)(SA) (SA)(SA)(RA)(RA)(RA)(RA)
Synthetic Tactile Sensor Design
mimics Merkel cell-slowly adapting type 1
(SA-1) afferents
mimics Meissner corpuscles-rapidly adapting (RA) afferents
Device Components
Materials used are poly(dimethylsiloxane) (PDMS) and polyimide or glass. Reservoir shape molded into PDMS, and electrodes laid onto the polyimide/glass.
Filling Techniques
Three different methods have been investigated:
1. Syringe2. Pump3. Channel Outgas Technique (COT)
(Monahan et al, 2001)
Monahan et al., Anal. Chem. 73: 3193-7 2001
Issues with Filling Techniques Air bubbles formed in reservoir with syringe and
pump methods.
For pump and COT method, sealing of PDMS where holes are made is necessary.
COT needs modification to allow for selective filling.
Fluid Loss from the Devices
Devices were filled using asyringe and sealed with
uncuredPDMS. They were kept at room temperature for a number ofweeks and the loss of fluid outof the devices was tracked.
Air bubbles on days 1, day 8 and day 16 respectively.
Mechanical Modeling of Sensor
Stress within PDMS layer
Fluid flow inside reservoir
Conclusions
Improvements to existing filling techniques or more techniques need to be explored.
Fluid loss is possible, so prevention is needed.
Fluid flow from reservoir is linear to applied pressure. Other geometries and models should also be investigated.
Acknowledgements:
A. P. Lee, PhD Jeffrey S. Fisher Wei-Yu (Tim) Tseng Undergraduate Research Opportunity
Program, UROP National Science Foundation, NSF