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