Micromachined needle arrays for drug delivery or fluid extraction - Design and fabrication aspects of fluid coupled arrays of hollow metallic microneedles

Micromachined needle arrays have been designed, fabricated, and characterized. The design includes arrays of 25 needles with fluid coupling channels and dual structural supports. Numerical modeling of fluid flow characteristics was performed, demonstrating that the needle coupling channels redistribute flow when the input or output ports are fully restricted. Micromachining technologies have been used to batch fabricate hollow metallic fluid coupled needle arrays. The significance of this work includes the development of the hollow metallic micromachined needle arrays for biomedical applications, as well as a discussion of structural, fluidic, and biological design considerations. The micromachined needle array has many advantages, including (a) reduced trauma at penetration site (small size), (b) greater freedom of patient movement (minimal penetration), (c) a practically pain-free drug delivery device (distribution of force), (d) precise control of penetration depth (needle extension length), and (e) they can be stacked and packaged into a 3-D device for fluid transfer.; There is a demand for a needle device that can subcutaneously deliver medication without the usual discomfort associated with current intravenous injection needles. To address this demand, a fluid coupled micromachined needle array is designed and fabricated. The array is composed of hollow metallic microneedles, fabricated on top of a silicon substrate, using micromachining surface fabrication techniques. The optimum design for the needle coupling channels was investigated using an ANSYS finite element numerical model.