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.

Dynamics of glass-forming liquids. XVI. Observation of ultrastable glass transformation via dielectric spectroscopy

“…Ultrastable IMC glass films were prepared by means of PVD. Details on the deposition procedure onto the interdigitated electrode (IDE) cells (ABTECH Scientific, Inc.) 40,41 have been reported previously. 42 The base pressure inside the PVD chamber was 5 × 10 −8 torr.…”

Quantum effects in the dynamics of deeply supercooled water

“…Dielectric measurements of deposited water were carried out using the IDE cell [53] purchased from ABTECH Scientific, Inc (IME 1050.5-FD-Au-U). The IDE structure consists of 50 pairs of Au electrode fingers.…”

Suppression ofβRelaxation in Vapor-Deposited Ultrastable Glasses

“…[ [15][16][17] Recently, novel glasses that exhibit remarkable stability have been prepared by physical vapor deposition [33]. The key recipe for the formation of such ultrastable glasses is to deposit the materials at substrate temperatures around 0.85T g .…”

“…We performed in-situ dielectric measurements to probe the relaxation dynamics of glasses that were vapor-deposited onto high precision, microlithographically fabricated interdigitated electrode cell using an ultra-precision capacitance bridge ( Fig. 1a and b) [17]. Experimental details are presented in supporting online materials [18].…”