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.