Concentration landscape generators for shear free dynamic chemical stimulation

Abstract

In this paper we first introduce a novel fabrication process, which allows for easy integration of thin track-etched nanoporous membranes, within 2D or 3D microchannel networks. In these networks, soluble chemical compounds can diffuse out of the channels through well-defined and spatially organized microfabricated porous openings. Interestingly, multiple micron-scale porous areas can be integrated in the same device and each of these areas can be connected to a different microfluidic channel and reservoir. We then present and characterize several membrane-based microdevices and their use for the generation of stable diffusible concentration gradients and complex dynamic chemical landscapes under shear free conditions. We also demonstrate how a simple flow-focusing geometry can be used to generate "on-demand" concentration profiles. In turn, these devices should provide an ideal experimental framework for high throughput cell-based assays: long term high-resolution video microscopy experiments can be performed, under multiple spatially and temporally controlled chemical conditions, with simple protocols and in a cell-friendly environment.

Microfluidic Microdialysis: Spatiotemporal Control over Solution Microenvironments Using Integrated Hydrogel Membrane Microwindows

“…(6) The fabrication strategy is relatively simple, requiring little more equipment than is standard in most research laboratories. (7) HMMs do not interfere with optical access to the sample, whereas, e.g., track-etched membranes used to introduce solute to a channel from above or below [11] interfere with the optical path. Instead, sample and reservoir channels can lie entirely within a single focal plane, allowing high-resolution gradient visualization within microscale regions and improved synchronization with reservoir channel flow switching.…”

Real-time concentration monitoring in microfluidic system via plasmonic nanocrescent arrays

“…In light of above, microfluidic system with capability of generating tunable concentrations as well as real-time probing is of great importance in the future complex on-chip bio/chemical processes. Limited research has yet concentrated on generation of dynamically controllable analyte concentrations combined with real-time on-chip effective and accurate concentration monitoring (Morel et al, 2012;Toetsch et al, 2009). In this work, we first designed and fabricated nanocrescent samples via electron beam lithography (EBL) with different geometries.…”

In vitro quantitative analysis of Salmonella typhimurium preference for amino acids secreted by human breast tumor

“…The most critical drawback of hydrogel member based system, however, is that the hydrogels are not robust without an aqueous environment and the volume of the hydrogels can be changed significantly depending on the amount of the water absorption [14]. Moreover, the diffusion-based microfluidic devices which can generate the multiple chemical gradients have been developed [18][19][20][21]. Nevertheless, these devices have some drawbacks as comparing with the proposed device.…”

“…Nevertheless, these devices have some drawbacks as comparing with the proposed device. In some cases, the devices were constructed with complex multilayered microfluidic parts so that it is complicated to fabricate the devices [18][19][20]. In other case, it is not easy to realize the spatio-temporal control of the chemical gradient direction [21].…”