A NEW MICROFLUIDIC DEVICE INTEGRATED WITH QUARTZ CRYSTAL MICROBALANCE TO MEASURE COLLOIDAL PARTICLE ADHESION
Polystyrene particles simulating bacteria flow down a micro-channel in the presence of potassium chloride solution. Depending on the ionic concentration or flow rates, portion of the particles are trapped on the glass substrate due to intrinsic surface forces. A novel quartz crystal microbalance (QCM) is built into the microfluidic device to track the real-time particle deposition by shift of the resonance frequency. The new technique is promising to quantify water filtration.
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NSF-PAR ID:
10350792
Journal Name:
Proceedings of the ASME 2021 International Mechanical Engineering Congress and Exposition
Volume:
5
3. We identify a phenomenon where the onset of channel flow creates an unexpected, charge-dependent accumulation of colloidal particles, which occurs in a common-flow configuration with gas-permeable walls, but in the absence of any installed source of gas. An aqueous suspension of either positively charged (amine-modified polystyrene; a-PS) or negatively charged (polystyrene; PS) particles that flowed into a polydimethylsiloxane (PDMS) channel created charge-dependent accumulation 2 to 4 min after the onset of flow. We unravel the phenomenon with systematic experiments under various conditions and model calculations considering permeability of the channel walls and$CO2$-driven diffusiophoresis. We demonstrate that such spontaneous transport of particles is driven by the gas leakage through permeable walls, which is induced by the pressure difference between the channel and the ambient. Since the liquid pressure is higher, an outward flux of gas forms in the flow. We also observe the phenomenon in a bacterial suspension ofVibrio cholerae, where the fluorescent protein (mKO; monomeric Kusabira Orange) and bacterial cells show charge-dependent separation in a channel flow. Such experimental observations show that diffusiophoresis of charged particles in an aqueous suspension can be achieved by having gas leakage through permeable walls, without any preimposed ion-concentration gradient in themore »