Rapid and Cost-Effective In situ Fabrication of Nanoporous Membranes in Microfluidic Devices for Biomedical and Environmental Applications

TL;DR

This study tackles the challenge of fabricating nanoporous membranes within microfluidic devices using a simple, cost-effective in-situ approach. It introduces a single-step coagulation process where cellulose acetate dissolves in DMF and 1-hexanol and forms cellulose acetate nanoparticles at the water–DMF interface under continuous antisolvent flow, coagulating into nanoporous membranes whose porosity can be tuned by flow rate and CA concentration. The resulting membranes exhibit pore sizes around 100–200 nm (average ~160 nm) and demonstrate dye separation across multiple cycles and retention of microplastics, indicating utility for both biomedical and environmental applications. The method offers scalable, rapid fabrication of micro/nanoporous membranes in microfluidic devices, enabling integrated filtration, sensing, and separation in compact systems.

Abstract

Micro/nanoporous membranes have been used extensively in biological and medical applications associated with filtration, particle sorting, cell separation, and real-time sensing. Expanding its applications to microfluidics offers several advantages, such as precise control over fluid flow rates, regulated reaction times, and efficient product extraction. This study demonstrates a simple, cost-effective, rapid, single-step method for the synthesis of nanoporous membranes within a microfluidic device. The membrane is prepared by filling up the microchamber with cellulose acetate dissolved in N, N-dimethylformamide, and 1-hexanol, followed by the continuous flow of water as an antisolvent. Mixing CA-DMF with antisolvent water leads to an in-situ synthesis of cellulose acetate nanoparticles (CANPs) at the Water-DMF interface. The continuous flow of water ensures the coagulation of CANPs, forming nanoporous membranes. The thickness, porosity, and wettability of the membrane are dependent on the flow rate of water and the concentration of CA dissolved in DMF. Apart from its wide application in cell and biomolecule separation, this membrane can be used to detect biomarkers or pathogens in clinical samples. Additionally, these nanoporous membranes can be used to detect and filter environmental contaminants such as heavy metals, pesticides, and emulsified oil from water. In summary, the synthesis of CANP nanoporous membranes within microfluidic channels with adjustable porosity enhances the potential uses of micro/nanomembranes in both healthcare and environmental contexts.

Figures (9)

• Figure 1: (A) Schematic diagram illustrating the fabrication process of the microfluidic channel. (B) Fabricated T-shaped microfluidic channel.
• Figure 2: Fabrication of cellulose acetate membrane within a microfluidic channel, occurring at the interface of water and a mixture of cellulose acetate, DMF, and 1-hexanol.
• Figure 3: Longitudinal and transverse cross-sectional representation of fabrication of cellulose acetate membrane within the microfluidic channel, with continuous flow of antisolvent water. As DMF diffuses into the water, cellulose acetate nanoparticles (CANPs) continuously form and coagulate.
• Figure 4: (A) Nanoporous cellulose acetate membrane fabricated inside the microfluidic channel. (B) FESEM image of the nanoporous membrane. (C) Depth map of the membrane. (D) Pore space segmentation of the membrane. (E) Pore size distribution plot. Images (C), (D), and bar plots (E) were obtained by performing image analysis of the image (B).
• Figure 5: Filtration of methyl red dye using cellulose acetate nanoporous membrane within microchannel. The inlet introduces a high-concentration methyl red solution, which is filtered through the membrane, resulting in a lower-concentration permeate exiting from the outlet.