Microneedle fabrication and applications

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Micro-nanoscale science and technology has become one of the fastest growing research areas in recent years. Besides the conventional semiconductor industry, micro-nanofabrication techniques using cleanroom facility are also widely employed in industries including microelectromechanical systems, displays, photovoltaics, data storage, biomedical sensors, and optical communications. For this research program, top down microfabrication techniques using cleanroom facility will be utilized to fabricate the microneedle devices. Microneedle technologies have become beneficial for realizing minimally invasive platforms capable of transdermal drug delivery and body fluid sampling and diagnostics. Microneedles are anticipated to mitigate the shortcomings associated with lancets and hypodermic needles. It requires only a small area of skin to be penetrated at a limited depth, resulting in minimal irritation of dermal layers associated with pain and tissue damage. This research program will focus on developing novel hollow microneedle fabrication technology and its future applications for drug delivery and disease diagnosis. Compared to solid microneedles, hollow ones offer much better fluidic control for drug delivery. In our previously funded Discovery grant, we developed a fabrication process for (short) hollow silicon microneedles, which are capable of extraction of interstitial fluid for allergy test, yet with poor reproducibility due to the limited needle length. For drug delivery, and to a less degree, extraction of interstitial fluid for diagnosis, however, taller microneedles are needed for medical applications where the target delivery site is far below the skin surface or the skin is too flexible or too thick. As such, in the next five years, we will expand on our findings to fabricate longer (up to 1.5mm, compared to currently record length of ~1mm for hollow silicon microneedle) and sharper needles, as well as microfluidic platform for drug delivery and extraction of body fluid through microneedle. Cutting edge microfabrication technology including dry plasma etching and wafer bonding and thoughtful design of the fabrication procedure will be explored to realize the objectives for this research program. Microneedle technology has a wide and growing range of applications for bio-sensing and drug delivery including potentially the painless (or some minor pain, depending on needle length) delivery of COVID-19 vaccine. The ultra-long hollow microneedle to be developed in this research will be the key enablers for microneedle technology. Students will receive intensive hands-on training in device design and fabrication. Many industrial sectors of importance to Canada could exploit the microneedle technologies and the micro-nanofabrication techniques, and this program will create knowledge, innovation and technical experts in this growing field.