The present study was designed to identify the most suitable polymeric microneedle (MN) array design for use as an electrically responsive device capable of providing both sustained and on-demand percutaneous drug delivery both in vitro and in vivo. Soluble MN arrays loaded with a range of small to large molecules were fabricated from aqueous blends of 20% w/w poly(methyl vinyl ether eo maleic acid) (PMVEIMA). Novel hydrogel forming MN arrays were fabricated from aqueous blends containing 15% w/w PMVEIMA and 7.5% w/w poly(ethyleneglycol) (PEG, M; = 10 kDa). MN arrays were fabricated in a laser-engineered micro-moulding process. Hydrogel MN arrays were integrated with drug loaded reservoir patches. Whilst the combination of iontophoresis with both polymeric MN systems led to enhanced transdermal delivery of all drug molecules investigated in vitro, the electro- responsive nature of the hydrogel forming MN arrays enabled the sustained passive delivery and the electrically stimulated bolus delivery of the proteins insulin and bovine serum albumin in vivo. As such, this system may have great potential for the pulsatile transdermal delivery of therapeutic peptide/protein agents.