title: Design considerations in the use of interdigitated microsensor electrode arrays (IMEs) for impedimetric characterization of biomimetic hydrogels.
abstract: Microlithographically fabricated interdigitated microsensor electrodes (IMEs) were cleaned, surface activated, chemically functionalized (amine) and derivatized with an Acrloyl-PEG-NHS to receive a spun-applied monomer cocktail of UV polymerizable monomer. IMEs were 2050.5, 1550.5, 1050.5 and 0550.5 possessing lines and spaces that were 20, 15, 10, and 5 μm respectively; 5 mm line lengths and were 50 lines on each opposing bus. Bioactive hydrogels were synthesized from spun-applied and UV-crosslinked tetraethyleneglycol diacrylate (TEGDA) (crosslinker), 2-hydroxyethylmethacrylate (HEMA), polyethyleneglycol(200) monomethacrylate (PEGMA), N-[tris(hydroxymethyl)methyl]-acrylamide (HMMA) and poly(HEMA) (MW 60,000) (viscosity modifier) and 2,2-dimethoxy-2-phenylacetophenone (DMPA) (photoinitiator) to produce a 5 μm thick p(HEMA-co-PEGMA-co-HMMA) hydrogel membrane on the IMEs. Unmodified and hydrogel coated IMEs where characterized by AC electrical impedance spectroscopy using 50 mV p-t-p over the frequency range from 10 Hz to 100 kHz in aqueous PBS 7.4 buffer and in buffer containing 50 mM [Fe(CN)(6)](3-/4- ) solution at RT. Impedimetric responses were found to scale with the device geometric parameters. Equivalent circuit modeling revealed deviations from ideality at lower device dimensions suggesting an implication of the substrate surface charge on the double layer capacitance of the electrodes. Diffusion coefficients derived from the Warburg component are in accord with literature values.
authors.affiliation: Biomanufacturing Research Institute and Technology Enterprises and Department of Pharmaceutical Sciences, North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA.
authors.forename: Liju
authors.initials: L
authors.lastname: Yang
authors.forename: Adilah
authors.initials: A
authors.lastname: Guiseppi-Wilson
authors.forename: Anthony
authors.initials: A
authors.lastname: Guiseppi-Elie
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002021:Buffers; D017097:Electric Impedance; D004566:Electrodes; D004867:Equipment Design; D005292:Ferricyanides / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D008567:Membranes, Artificial; D055616:Microtechnology / Q000295:instrumentation*; D010710:Phosphates / Q000737:chemistry; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry
chemical_list: D002021:Buffers; D005292:Ferricyanides; D020100:Hydrogels; D008567:Membranes, Artificial; D010710:Phosphates; D011102:Polyhydroxyethyl Methacrylate; C028033:potassium ferricyanide