A miniaturized flow reaction chamber for use in combination with QCM-D sensing

Abstract

A miniaturized flow chamber for quartz crystal microbalance with dissipation monitoring (QCM-D) has been developed. The main purpose was to reduce the total liquid sample consumption during an experiment, but also to gain advantages with respect to kinetics and mass transport by reducing the boundary diffusion layer. The bottom of the flow chamber is a QCM-D sensor surface, on which a polydimethylsiloxane spacer ring, fabricated onto a poly(methyl methacrylate) lid, is placed symmetrically around the QCM-D electrode (diameter *10 mm). The spacer ring defines the inner chamber height (typically 40-50 lm) and provides sealing. Through the lid, there are inlet and outlet channels. The typical chamber volume is in the range of 2.5-3.5 ll (with a 10 ll dead volume). In flow mode, we have operated the cell at flow rates of 6-50 ll/ min, i.e., volume turnovers of 2-17 per min. As a model system, to test the microcell, the formation of supported phospholipid bilayers on a SiO 2 surface was studied. For comparison, the same process was studied in a commercially available QCM-D equipment with significantly larger total volume (by a factor of 20). The decrease in effective sample consumption to produce a bilayer on the sensor surface in the chamber was approximately proportional to the decrease in chamber volume. Smaller volume also reduced the liquid exchange time. Potential improvements of the chamber include further optimization of the flow profile and, in addition, further miniaturization by decreasing the chamber height and the sensor radius.

A practical guide to quartz crystal microbalance with dissipation monitoring of thin polymer films

“…Another resolution is to degas the solution prior to flow. 24,70 Asides from F I G U R E 3 (A) Schematic illustration of detachment (delamination and dissolution) and subsequent QCM-D response. (B) When a thin film of PEDOT-S:H (left panel) is submerged in aqueous electrolyte (middle panel), and is electrochemically oxidized in an aqueous electrolyte (right panel).…”

“…A more effective answer involves equilibrating the flow solution to the intended chamber temperature prior to the experiment, thus eliminating the temperature difference. Another resolution is to degas the solution prior to flow 24,70 . Asides from the flow of bubbles through the system, it is also possible to have smaller bubbles deposited on the sensor itself 70 .…”

A Survey of the 2010 Quartz Crystal Microbalance Literature

“…The QCM flow chamber was miniaturised in order to reduce sample volumes and the associated boundary diffusion layer. The formation of phospholipid bilayers was used as a test case and total sample volumes were twenty fold lower than commercial QCM equipment (Ohlsson et al ., ). Furthermore, a wireless QCM system was developed where the shear vibration excitation and detection was achieved using antennas and the system was demonstrated using antigen‐antibody interactions (Ogi et al ., ).…”

Integration of a Miniature Quartz Crystal Microbalance with a Microfluidic Chip for Amyloid Beta-Aβ42 Quantitation

“…A miniature QCM with a quartz diameter of 3 mm fixed on a PDMS flow cell for detecting protein A from Staphylococcus aureus in liquid phase was reported [ 22 ]. To reduce the boundary diffusion layer and total sample consumption, a miniaturized flow reaction chamber with a volume of 3.5 µL was developed for a quartz crystal microbalance with dissipation monitoring [ 23 ]. Meanwhile, microfluidic devices based on polydimethylsiloxane (PDMS) possess the advantages of low cost, rapid fabrication and excellent biocompatibility compared to those on quartz, silicon or glass.…”