Integrated MEMS microneedles and microelectrode arrays for biomedical applications

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There are many drawbacks to hypodermic needles, such as insertion pain, tissue trauma, and expertise needed to perform an injection. Microneedle arrays promise potentially painless extraction and infusion by penetrating only the upper part of the skin, avoiding the nerves. Hollow and solid microneedles are the two most common designs. Hollow microneedles work as their larger counterparts, with fluid flow through a tube piercing the skin. However they can suffer from clogging of the opening and have the potential to break. Solid microneedles are coated with a therapeutic agent, allowing drug molecules to dissolve into the surrounding tissue. The dosage depends on the microneedle area and therefore the yield is limited. This work will investigate new hollow microneedle designs and materials to overcome clogging issues and improve robustness.. To overcome the solid microneedle yield issue, new designs will be explored, such as the creation of microfluidic channels next to the base of the solid microneedles, to enable delivery of relevant amounts of drugs through the pierced tissue. Microfabrication methods are ideal to create microneedle arrays, as the materials are biocompatible, robust and designed for large-scale integration with other micro manufacturing processes. Integrating microneedles with suitable micropumping methods will enable a compact drug delivery or fluid extraction system to be developed. Physiological fluids such as blood contain many bio particles and pose difficulties as they can clog microfluidic systems and shear forces from mechanical pumping methods can damage cells. To tackle these challenges, non-mechanical micropumping methods known as electrokinetic micropumping will be investigated. Fluid is moved via electric fields and thus there are no moving parts, like a valve or membrane, for particles to adhere to or be damaged by. Electrokinetic systems are also inherently easier to control via digital electronics, making them ideal for integration with a microcontroller, enabling precise control of fluid flow in the microneedle system. This research will move from the bench to the bedside, by integrating microneedles and micropumps to create a microneedle system that can be used without direct medical intervention. We will achieve this by focusing on three specific aims: 1) Development of new hollow and solid microneedles 2) Development of electrokinetic micropumps 3) Creation of integrated microneedle systems. The diverse HQP supported by this work will learn cutting-edge microfabrication and simulation techniques. They will validate their ideas by designing, fabricating and testing microneedle systems. As with past HQP, this program will prepare them for future employment in the biomedical industry and academia. This research will lead to new technologies for drug delivery, improving quality of life for patients and benefitting the economy through reducing healthcare expenditures.