Fear of needles is prevalent, estimated at around 10% in adults worldwide. We report on new solid microneedle arrays made of gold in combination with micro holes to replace traditional hypodermic needles for drug delivery. This work provides a breakthrough for painless drug delivery with precise control over the microneedle width, height, array density and position. Results show successful delivery of liquids through a parafilm layer representing the stratum corneum of the human skin.
Microneedles are an emerging technology that offer an alternative to traditional hypodermic needles for drug and vaccine delivery. Less than 1 mm in length, microneedles can penetrate the skin with little to no pain making them a suitable option for the 1-in-10 people that may avoid seeking medical care due to needle phobia. However, there are significant challenges with adapting existing microneedle fabrication methods for large scale manufacturing while matching the repeatability, reliability, and cost of current hypodermic needle mass production processes. In this work we present a novel method of fabricating microneedles using a modified automated wire bonding process that is highly suited for mass production due to existing widespread use of this process and equipment in the semiconductor industry. Microneedle arrays of different densities were fabricated on FR-4 based printed circuit board substrates using this automated process and tested by inserting into porcine skin tissue to determine insertion forces. The required insertion force generally increased with increasing array density due to the “bed of nails” effect and decreased with increasing insertion speed due to the viscoelastic properties of porcine skin tissue. Characterizing the correlations between insertion force, insertion speed, and array density are important for designing microneedle-based devices and applicators that can reliably penetrate skin. Microneedle arrays were also successfully created by automated wire bonding on polyimide-based printed circuit boards to demonstrate that this process can be done on flexible substrates. Further investigation with larger samples sizes is required to expand on the preliminary findings of this work.
Needles are a key, and very common, component of modern medicine, used primarily for drug delivery and blood withdrawals. There are, however, many drawbacks to their use, such as insertion pain, tissue damage, and the development of fears and avoidance of medical care, especially in younger patients. Needle phobia (extreme fear of needles associated with avoidance) affects 1 in 10 people, who are then likely to avoid seeking any medical care. In addition, there are significant populations living with medical conditions, such as diabetes, that require multiple daily injections for effective management of their chronic health condition. Microneedles are small needles less than 1 mm in length that penetrate the skin with minimal or no pain. Microneedles can also reduce tissue damage that can lead to scarification and localized drug resistance in high frequency injection sites. By using high accuracy automated microfabrication techniques, we have developed a new method of quickly and effectively making microneedle arrays capable of interfacing with existing technologies, such as insulin pens and traditional syringes. This work shows a microneedle system which is inexpensive to mass fabricate and preliminary results point to minimal patient pain compared to other microneedle devices. The microneedle construction from a thin metal wire means there is minimal risk of fracture and deposition of material in the dermis that traditional polymeric or silicon microneedles face. This work presents the basis for a pain free injection system that will have significant impacts on patient health, both physical and mental, and healthcare system costs.
Microfluidic systems are growing increasingly prevalent as the future for modern medicine. With the transition to miniaturized systems, comes a growing need for equally miniaturized fluid delivery and control mechanisms. Electrokinetic pumping systems are uniquely suited to this task due to low power requirements and ease of scalability. Electrothermal micropumps in particular are efficient at manipulating high conductivity fluids, such as biofluids. This work describes methods by which electrothermal pumps are effectively simulated, fabricated, and tested with unique improvements designed to improve efficiency and adoptability in microfluidic systems.
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