Micromachined needle arrays for drug delivery or fluid extraction

Abstract

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.

Axial and shear fracture strength evaluation of silicon microneedles

“…In recent times, numerous types of microneedles have been fabricated and used for transdermal drug delivery (Gardeniers et al 2003;McAllister et al 2003;Martanto et al 2004;Park et al 2005;Gill and Prausnitz 2007), vaccine delivery (Griss and Stemme 2003), fluid analysis and sampling (Brazzle et al 1999), dialysis (Zahn et al 2005) and cellular DNA delivery (McAllister 2000) among other applications.…”

Silicon micromachined hollow microneedles for transdermal liquid transport

“…The in-plane version is the most convenient to fabricate with state-of-the-art planar technology, comprising surface micromachining and different techniques of (sil-icon) etching, and creates a good degree of flexibility with respect to different needle designs. Illustrative examples are the sophisticated hollow neural probes of Wise et al, fabricated by anisotropic wet etching of a silicon substrate combined with deep diffused boron etch stops and having CMOS electronic circuitry integrated on the chip [2], [3], the microneedles manufactured by anisotropic wet etching of a silicon substrate, with surface micromachined polysilicon-based fluidic channels on them, by Pisano's group [4], [5], which were later refined by the use of silicon-on-insulator substrates and isotropic etching [6], the hollow micromachined needle arrays by Brazzle et al [7], [8], and the surface micromachined polysilicon microneedles with permeable polysilicon on one side which serves as a microdialysis membrane [9], [10].…”

Current Trends in MEMS Drug Delivery Techniques

“…These puncture the skin and then infuse the drugs that are in a liquid formulation through the needle bores into the tissue. These do not have the drug capacity limitation as in the case of solid needles and arbitrary quantities of drugs in liquid formulation can be used [15], [16], [17]. However, they pose the danger of breaking off in the skin as they are hollow and less structurally stable than solid microneedles [18] (See Fig.…”