Graduation Year


Document Type




Degree Granting Department

Electrical Engineering

Major Professor

Shekhar Bhansali, Ph.D.

Committee Member

Sangchae Kim, Ph.D.

Committee Member

William Lee, Ph.D.

Committee Member

Thomas Koob, Ph.D.


Skin, Drie, Porous silicon, Penetration force, Fracture force


Hollow biocompatible microneedle arrays were designed and fabricated using two different bulk micromachining techniques-Deep Reactive Ion Etching and Coherent Porous Silicon technology to investigate their reliability for transdermal applications. An in-house experimental setup was developed for microneedle fracture and split thickness penetration force measurements. Out of plane needle array configurations (100and#956;m needle length) with intra array geometric variations including needle shape, diameter, intra-array pitch and density (1a 625) were characterized on cadaver skin to predict skin barrier penetration without fracture. Use of microneedle array as transdermal patch necessitates reliable penetration and not just pushing against stratum corneum like a bed of nails. Critical in plane fracture tests were conducted on single microneedle columns with different geometry to validate the failure mechanism with force quantification relations. Preliminary penetration characterization was performed on skin like polymer followed by direct testing on cryogen preserved cadaver skin. Compressive and indentation test were performed on both excised skin and polymer to analyze their mechanical behavior on loading and establish a mechanical correlation. Finite element modeling using ANSYS was done to examine the effect of shear loading on the needles due to lack of experimental verification.