Integrated MEMS microneedles and microelectrode arrays for biomedical applications

皮下注射针头有许多缺点，如插入疼痛、组织创伤和进行注射所需的专业知识。微针阵列只穿透皮肤的上部，避开神经，有望实现无痛的提取和注射。空心微针和实心微针是两种最常见的设计。空心微针的工作原理和它们的大针头一样，液体通过管子穿过皮肤。然而，它们可能会堵塞开口，并有可能破裂。固体微针被一种治疗剂包裹，允许药物分子溶解到周围的组织中。剂量取决于微针面积，因此产率是有限的。这项工作将研究新的空心微针设计和材料，以克服堵塞问题，提高鲁棒性。为了克服固体微针的产量问题，将探索新的设计，例如在固体微针的底部附近创建微流体通道，以便通过穿孔组织输送相应数量的药物。微制造方法是制造微针阵列的理想方法，因为这些材料具有生物相容性，坚固耐用，并且设计用于与其他微制造工艺大规模集成。将微针与合适的微泵方法相结合，将能够开发出紧凑的药物输送或流体提取系统。血液等生理液体含有许多生物颗粒，它们会堵塞微流体系统，而机械泵送方法产生的剪切力会损害细胞，这给研究带来了困难。为了解决这些挑战，将研究非机械微泵方法，即电动微泵。流体是通过电场移动的，因此没有像阀门或膜这样的运动部件来附着或损坏颗粒。电动系统本身也更容易通过数字电子设备进行控制，这使得它们非常适合与微控制器集成，从而可以精确控制微针系统中的流体流动。这项研究将通过整合微针和微泵来创建一个无需直接医疗干预即可使用的微针系统，从实验台走向床边。我们将通过三个具体目标来实现这一目标：1)开发新的空心和固体微针；2)开发电动微泵；3)创建集成微针系统。这项工作支持的各种HQP将学习尖端的微加工和模拟技术。他们将通过设计、制造和测试微针系统来验证他们的想法。与过去的HQP一样，这个项目将为他们未来在生物医学行业和学术界的就业做好准备。这项研究将带来药物输送的新技术，提高患者的生活质量，并通过减少医疗保健支出使经济受益。

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.