Metallization of Organically Modified Ceramics for Microfluidic Electrochemical Assays

Abstract

Organically modified ceramic polymers (ORMOCERs) have attracted substantial interest in biomicrofluidic applications owing to their inherent biocompatibility and high optical transparency even in the near-ultraviolet (UV) range. However, the processes for metallization of ORMOCERs as well as for sealing of metallized surfaces have not been fully developed. In this study, we developed metallization processes for a commercial ORMOCER formulation, Ormocomp, covering several commonly used metals, including aluminum, silver, gold, and platinum. The obtained metallizations were systematically characterized with respect to adhesion (with and without adhesion layers), resistivity, and stability during use (in electrochemical assays). In addition to metal adhesion, the possibility for Ormocomp bonding over each metal as well as sufficient step coverage to guarantee conductivity over topographical features (e.g., over microchannel edges) was addressed with a view to the implementation of not only planar, but also three-dimensional on-chip sensing elements. The feasibility of the developed metallization for implementation of microfluidic electrochemical assays was demonstrated by fabricating an electrophoresis separation chip, compatible with a commercial bipotentiostat, and incorporating integrated working, reference, and auxiliary electrodes for amperometric detection of an electrochemically active pharmaceutical, acetaminophen.

Simultaneous Culturing of Cell Monolayers and Spheroids on a Single Microfluidic Device for Bridging the Gap between 2D and 3D Cell Assays in Drug Research

“…[ 28,29 ] On the untreated, planar areas, the native Ormocomp surface supported strong adhesion of both cells (Figure 1f) and metals (Figure 1g), which facilitated integration of cell‐compatible gold electrodes for impedance detection. The cell compatibility of native Ormocomp [ 22–26 ] as well as the Ormocomp metallization protocols [ 30 ] has been thoroughly established in previous literature. In this study, the impedance spectra were measured after cell seeding, once every hour for 96 h, using frequency range of 5–100 000 Hz (Figure 1h).…”

“…For noninvasive monitoring of cell monolayer growth based on electrical impedance sensing, two pairs of thin‐film gold electrodes were implemented onto the planar Ormocomp surfaces between the microwell arrays (Figure 1a). First, a 10 nm‐thick titanium layer was deposited over the entire wafer by evaporation (IM‐9912 evaporator, Instrumentti Mattila, Mynämäki, Finland) under same condition which pointed in Bonabi et al [ 30 ] to promote gold adhesion onto the Ormocomp substrate (Figure S1D, Supporting Information). Next, a 100 nm‐thick gold layer was deposited by evaporation (Figure S1E, Supporting Information) and patterned by photolithography.…”

Microfluidic Analysis Techniques for Safety Assessment of Pharmaceutical Nano‐ and Microsystems

“…Metallization processes (sputtering or evaporation) typically rely on cleanroom equipment, but are fairly well established for e.g., glass. Instead, metallization of polymers typically suffers from poor adhesion (especially on PDMS [52]) and necessitates development of custom, material-specific processes (see, e.g., metallization of organically modified ceramics [53]). At best, however, combination of optical and impedance detection allows for long-term culturing with continuous parallel and mutually independent monitoring of the cell growth rates by means of impedance measurements and of specific other cellular events by means of optical or fluorescence microscopy [49].…”

Body-Implantable RFID Tags Based on Ormocer Printed Circuit Board Technology

“…2(f) shows a similar tag based on Al metallization, indicating the versatility of the developed PCB technology. It is noted that metallization can also be achieved by using deposited metallic films [11]. However, lamination of metal foils was adopted in this study to demonstrate low cost manufacturing for future large scale commercialization.…”

“…In this study Ormocomp® was chosen as it is readily available and extensively used in the fabrication of various microdevices such as microfluidic devices [9][10][11] and cell growth scaffolds [6,7]. The optical transparency of Ormocomp® allows for the fabrication of optical waveguides and sensors [12][13][14][15].…”