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Artificial Mechanical Skin Model


Development of an Artificial Mechanical Skin Model for Microneedle Insertion Profiling

Project Description

With the ongoing development of a large variety of microneedles, characterizing microneedle-soft tissue interactions and mechanical testing of microneedles prior to their use in transdermal drug delivery emerge as major challenges. Microneedles must be tested against human skin to ensure that desired characteristics of microneedles (strength, resistance to irreversible deformation, required forces to penetrate the stratum corneum) are achieved for multiple insertions at a target depth in a repeatable manner. The accessibility of human skin samples for this purpose of microneedle testing is, in general, limited, and the mechanical properties of skin can vary from sample to sample. An alternative artificial mechanical human skin model would be valuable as a standard benchmark and for its availability.
This project involves the development of a polymer-based composite skin model that mimics the mechanical properties of the human skin layers. A number of polymers were used to model the epidermal layers of skin, including the stratum corneum, and the dermis by adjusting their stiffness, strain, and failure characteristics. The compositions and characteristics of the individual layers in this composite skin model are selected for their similarity to the equivalent skin layers after nano-indentation, compression and ultimate tensile strength testing. Hollow metal microneedles, fabricated using photolithography and metal electrodeposition, were used for microneedle insertions into the artificial skin model. With the aid of optical microscopy and an in-house built microneedle insertion tool, microneedle insertions into human skin and into the artificial skin model are monitored and profiled. The force applied by the microneedle to the skin surface during the insertion is recorded as a function of displacement, which allowed determining the point of microneedle penetration. From preliminary results, there was no statistically significant difference in the forces required to insert a microneedle into the artificial skin model compared to excised human skin. The artificial mechanical skin model would further allow for the development of repeatable and optimized microneedle insertion into skin to controlled depths with controlled insertion speeds and forces.

Faculty Supervisor(s)



    Sahan Ranamukha...