Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

In this paper, we discussed biocompatibility improvement and mechanical strength of the solid silicon (Si) microneedles for transdermal drug delivery systems. The pyramidal shape and sharp tip of microneedles are fabricated using an optimized Tetramethylammonium Hydroxide (TMAH) etching factors. The mechanical strength and biocompatibility of the microneedle array are enhanced after coating gold (Au) layer through metal sputtering technique. The needles thus fabricated are suitable for sustained transdermal drug delivery applications with a height of 250 μm and a base width of 52.8 μm, the aspect ratio of 4.73, and tip angle and diameter of 24.5° and 45 μm. The Vickers hardness value of 3800 Hv is obtained for the fabricated Au-coated solid Si microneedles. The attained Vickers hardness value is substantially higher than the skin resistive force. It shows that the capability of drug delivery by piercing these microneedles into the skin becomes readily feasible. © 2018, Springer-Verlag London Ltd., part of Springer Nature.

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International Journal of Advanced Manufacturing Technology

Fabrication and characterization of gold-coated solid silicon microneedles with improved biocompatibility

In this work, solid silicon (Si) microneedles with a higher aspect ratio and sharper tips are fabricated. Tetramethylammonium Hydroxide (TMAH) etching factors have been optimized and used to fabricate long and tapered microneedles. The needles thus fabricated are found to be suitable for transdermal drug delivery applications. The optimized etching factors include varying the concentration of TMAH, etching time, etching rates, temperature, and window size of optical mask. It is found that by increasing the window size, the etch rates in both vertical and lateral directions increase extensively. However, on increasing the temperature beyond 90 °C, etching becomes rapid and uncontrollable. In order to obtain microneedles with high aspect ratio, sample placement in the glass boat of TMAH setup and TMAH concentration should be manipulated to attain a higher etch rate in vertical direction compared to the lateral one. Solid silicon microneedles with an average height of 158 μm, base width of 110.5 μm, aspect ratio of 1.43, tip angle of 19.4° and tip diameter of 0.40 μm are successfully fabricated. A microhardness value of 44.4 (HRC) was obtained for the fabricated Si microneedles. This is 52.2 times higher than the skin Ultimate Tensile Strength (UTS), which makes insertion of microneedles through the skin safer and easier without any breakage. © 2016, Springer-Verlag London.