Microfluidic Imaging

Breckenridge MT, Egelhoff TT, Baskaran H (2010) A microfluidic imaging chamber for the direct observation of chemotactic ttansmi-gration. Biomed Microdevices 12 543-553... 

Microfluidic imaging techniques Microfluidics for imaging Optofluidic microscopes... 

This is another form of lens-free imaging scheme, where the object to be imaged is placed exactly on top of the sensor or camera. In 2005, Lange et al. [2] created a microfluidic imaging device that captured the shadow of a specimen placed over a CMOS sensor. One of the requirements for this method is that the light needs to be collimated so that the image does not get blurred. The distance between the source and the object also has an adverse effect on the image quality. 

Fig. 2.6.5 Hardware for high field NMR remote probe in (c) contains a relatively large saddle-detection. Photographs (a) and (b) show la- coil and is used for (flow) imaging. The detec-boratory-built remote detection probes with tor probe in (d) contains a microsolenoid coil both rf coils built into the same body (c), (d) for optimized mass sensitivity, which is parti-and (e) are detector-only remote probes that cularly useful for microfluidic NMR applica-can be inserted from the top or bottom into the tions. The same probe is shown in (e) with a NMR imaging assembly, so that the well mounted holder for a microfluidic chip that is...

Fig. 2.6.10 Specialized experimental set-up for microfluidic flow dispersion measurements. Fluid is supplied from the top, flows via a capillary through the microfluidic device to be profiled and exits at the bottom. The whole apparatus is inserted into the bore of a superconducting magnet. Spatial information is encoded by MRI techniques, using rf and imaging gradient coils that surround the microfluidic device. They are symbolized by the hollow cylinder in the figure. After the fluid has exited the device, it is led through a capillary to a microcoil, which is used to read the encoded information in a time-resolved manner. The flow rate is controlled by a laboratory-built flow controller at the outlet [59, 60].

The gas flow direction was from the top to bottom of the figure. No divergence is observed in the dispersion curve of the capillary, indicating that under the given conditions the dispersion of flow is small, and that this scheme is thus adequate to study the dispersion within a device of interest. This may appear unexpected, as microfluidic devices are usually assumed to exhibit laminar flow, however it can be explained by the fast lateral diffusion of individual gas molecules, which uniformly sample the whole cross section of the tube in a very short time compared with the travel time. Below each image, its projection is shown together with an independ-... 

Fig. 2.6.11 Flow dispersion profiles obtained with (a) a capillary, (b) with a model microfluidic chip device containing a channel enlargement, directly connected to a capillary and (c) with the same microfluidic chip connected to a capillary via a small mixing volume. A sketch of the model microfluidic device is placed at the right side of each image, drawn to...

For high-speed FLIM applications, including real-time imaging of biological tissue using endoscopes or macroscopes, as well as for imaging live cell dynamics and microfluidic systems, we have... 

A final example of MDFI exploiting polarization resolution is given in Fig. 4.12. This shows the application of optically sectioned TR-FAIM to image ligand binding in a microfluidic reactor [67], Solutions of a small dye molecule (Hoechst 33258) and a (nonfluorescing) 5.8 kbp DNA plasmid were mixed in a 50-/mi wide... 

Benninger, R. K. P., Hofmann, O., McGinty, J., Requejo-Isidro, J., Munro, I., Neil, M. A. A. and French, P. M. W. (2005a). Time-resolved fluorescence imaging of solvent interactions in microfluidic devices. Opt. Express 13, 6275-85. 

Fig. 16 Fluorescence images of LIVE/DEAD assays of the L929 cells encapsulated for 4 days (a) in the miniaturized PMBV/PVA hydrogel formed in the microfluidic chip, and (b) in the bulk PMBV/PVA hydrogel formed in the 96-well microplate. Green fluorescence indicates live cells and red fluorescence indicates dead cells. Scale bar 100 pm...

There are more issues and complexity to be considered if various micro-electromechanical (MEMS)-type devices are included in the macroelectronics tool kit. As described previously, the materials and devices required for TFTs and circuits can provide adequate electromagnetic (visible and RF) sensitivity for many image-type applications. These materials may also provide satisfactory performance in pressure and strain sensors. Nanotube/nanowire-based devices look promising for various chem-bio sensors.85 However, there is little that is known about the ability to integrate printed microfluidic devices (and other such devices with moving parts) into a roll-to-roll-type process. 

In this method, NWs can be aligned by passing a suspension of NWs through microfluidic channel structures, for example, formed between a poly(dimethylsiloxane) (PDMS) mold 49 and a flat substrate (Fig. 11.3a). Images of NWs assembled on substrate surfaces (Fig. 11.3b) within micro-fluidic flows demonstrate that virtually all NWs are aligned along the flow direction. This alignment readily extends over hundreds of micrometers, and... 

Scheme 4. Synthesis of the radiolabeled imaging probe [18F]FDG 28 in a PDMS-based microfluidic reactor...

Lee CC, Sui GD, Elizarov A, Shu CYJ, Shin YS, Dooley AN, Huang J, Dari-don A, Wyatt P, Stout D, Kolb HC, Witte ON, Satyamurthy N, Heath JR, Phelps ME, Quake SR, Tseng HR (2005) Multistep Synthesis of a Radio-labeled Imaging Probe Using Integrated Microfluidics. Science 310 1793— 1796... 

In addition to absolute pressure measurements, pressure sensors can be used to determine flow rates when combined with a well-defined pressure drop over a microfluidic channel. Integration of optical waveguide structures provides opportunities for monitoring of segmented gas-liquid or liquid-liquid flows in multichannel microreactors for multiphase reactions, including channels inside the device not accessible by conventional microscopy imaging (Fig. 2c) (de Mas et al. 2005). Temperature sensors are readily incorporated in the form of thin film resistors or simply by attaching thin thermocouples (Losey et al. 2001). 

Fig. 16.4 Fabrication and assembly of the NOSA platform with PDMS microfluidics. The three elements of the fabrication are shown with the left column showing the steps involved in fabrica tion of the photonic structure, the middle column showing the fabrication of the fluidics, and the right column the fabrication of the valve layer. The lower image shows the assembly of the three elements into an integrated device similar to that shown in Fig. 16.2d...

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