Swelling curve for crosslinked hydrogel films prepared from aqueous blends containing 20% w/w PMVE/MA, 7.5% w/w PEG and 3% Na₂CO₃ based on the increasing mass of the swelling array expressed as a percentage of the mass of a dry array (Means ± SD, n = 3) (A).

<p>Super swelling microneedle arrays prepared from aqueous blends containing 20% w/w PMVE/MA, 7.5% w/w PEG and 3% Na₂CO₃ as (<b>B</b>) xerogel and (<b>C</b>) post-swelling for 3 hours in PBS pH 7.4. t/S versus t swelling curves of super swelling hydrogel prepared from aqueous blends containing 20% w/w PMVE/MA, 7.5% w/w PEG and 3% Na₂CO₃ (Mean ± SD, n = 3) (<b>D</b>). Digital microscope images of super swelling hydrogel-forming MN (prepared from aqueous blends containing 20% w/w PMVE/MA, 7.5% PEG 10,000 and 3% Na₂CO₃) following the application of different forces (0.05, 0.18, 0.36, 0.71 and 0.9 N/needle). These images are representative of the percentage reduction in the heights of needles on the MN arrays observed following the application of the different forces (Means+SD, n = 3) (<b>E</b>). Digital images showing micropores in excised neonatal porcine skin following application of different forces and subsequent staining with methylene blue solution post microneedle removal (<b>F</b>). Attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectra of dry hydrogels prepared from aqueous blends containing: 20% w/w Gantrez S-97, 7.5% w/w PEG 10.000 non crosslinked (a) and crosslinked (b) materials; Na₂CO₃ (c) and 20% w/w Gantrez S-97, 7.5% w/w PEG 10.000 and 3% w/w Na₂CO₃ non crosslinked (d) and crosslinked (e) materials. The left panel shows a closer view of the carbonyl region for the same materials. A FTIR Accutrac FT/IR-4100 Series (Jasco, Essex, UK) equipped with MIRacle diamond ATR was used at room temperature. Samples were scanned and recorded in the region of 4000–400 cm⁻¹ at a resolution of 4.0 cm⁻¹. The obtained spectra were an average of 64 scans. A standard smoothing process was applied to all the spectra using the equipment software (<b>G</b>).