Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing

Abstract

Minimization and management of membrane fouling is a formidable challenge in diverse industrial processes and other practices that utilize membrane technology. Understanding the fouling process could lead to optimization and higher efficiency of membrane based filtration. Here we show the design and fabrication of an automated three-dimensionally (3-D) printed microfluidic cross-flow filtration system that can test up to 4 membranes in parallel. The microfluidic cells were printed using multi-material photopolymer 3-D printing technology, which used a transparent hard polymer for the microfluidic cell body and incorporated a thin rubber-like polymer layer, which prevents leakages during operation. The performance of ultrafiltration (UF), and nanofiltration (NF) membranes were tested and membrane fouling could be observed with a model foulant bovine serum albumin (BSA). Feed solutions containing BSA showed flux decline of the membrane. This protocol may be extended to measure fouling or biofouling with many other organic, inorganic or microbial containing solutions. The microfluidic design is especially advantageous for testing materials that are costly or only available in small quantities, for example polysaccharides, proteins, or lipids due to the small surface area of the membrane being tested. This modular system may also be easily expanded for high throughput testing of membranes. Video LinkThe video component of this article can be found at

Printing-Assisted Surface Modifications of Patterned Ultrafiltration Membranes

“…After this treatment, scanning electron microscopy showed that the membrane surface and pores that were previously covered by the photoinitiator coating became visible again (Figure S3). Membrane performance testing utilized a custom designed 3D printed flow cell 6,34 in which four membranes were tested in four separate cells in parallel. High initial flux conditions (200 LMH) were chosen to significantly accelerate membrane fouling, 39−41 and 24 h fouling runs were performed at constant pressure with secondary treated wastewater.…”

“…29−33 Herein, patterned UV light from a threedimensional (3D) printer with DLP technology was adapted to initiate grafting of polymers onto surfaces of membranes. This stereolithographic technique achieved a striped pattern in three different polymer compositions and was tested in a microfluidic cross-flow cell 6,34 in an orientation perpendicular or parallel to the direction of the inlet water flow. The aqueous feed test solution consisted of secondary treated wastewater, representing a complex mixture of salts, natural organic matter, colloidal material, and microbes.…”

Review of membranes in microfluidics

“…Lefebvre et al researched the flow of artificial microcapsules in microfluidic channels for determining the elastic properties of the membrane . Wardrip et al presented a three‐dimensionally printed microfluidic cross‐flow system . Warkiani et al studied the membrane fouling at the microscale using isopore filters .…”

“…32 Wardrip et al presented a three-dimensionally printed microfluidic cross-flow system. 33 Warkiani et al studied the membrane fouling at the microscale using isopore filters. 34 Zhan et al studied the enhanced pervaporation performance of multi-layer pdms/pvdf composite membrane.…”

Tuning of salt separation efficiency by flow rate control in microfluidic dynamic dialysis

“…Membrane-facilitated molecular separations play a key role in many large-scale industrial processes, ranging from seawater desalination to fruit juice clarification, and also in milliliter-scale sample processing in biomedical research laboratories (van Reis and Zydney 2007;Saxena et al 2009;Kazemi et al 2016). Miniaturization towards microliter volumes can be achieved by integrating membranes with microfluidic systems (de Jong et al 2006;Chen et al 2016;Roelofs et al 2015;Wardrip and Arnusch 2016;Han and Hwang 2018). Microfluidic chips also enable in situ microscopy of the membrane, e.g., to study membrane fouling, and electrical or optical characterization of the permeate and retentate phases, facilitating separation performance evaluation of novel membrane materials and transport mechanisms (Roelofs et al 2015;Kwak et al 2013;Kornreich et al 2014).…”