Surface potential of a three-layer microgel thin film on gold The sample was fabricated by spin-coating alternating layers of poly(N-isopropylacrylamide-co-acrylic acid) hydrogel particles and poly(allylamine hydrochloride) from pH 6.5 buffer onto a mercaptoethylamine-functionalized gold film on glass. The variation in surface potential is likely attributable to incomplete coverage of the three different microgel layers. The section shows three discrete potential levels on the sample as color, overlaid on the height data which is rendered as topography. 15µm scan. Imaged with the MFP-3D AFM. Sample and image courtesy of C. D. Sorrell and L. A. Lyon, Georgia Tech Chemistry.