Microdispenser

D. Wallace, Ink-jet based fluid microdispensing in biochemical applications. Nucl. Med. Biol. 21, 6-9... 

Figure 12.5. Photograph of microdispensing system depositing an inorganic dielectric dispersion onto a patterned, metallized polyester film. The pattern is of a transistor gate electrode array. The microdispensing head atomizes the dispersion, generating a liquid spray much like a dual orifice atomizer found on an airbrush.

Kornienko, O., Lacson, R., Kunapuli, P, Schneeweis, J., Hoffman, I., Smith, T., Alberts, M., Inglese, J., and Strulovici, B., Miniaturization of whole live cell-based GPCR assays using microdispensing and detection systems, /. Biomol. Screen., 9, 186, 2004. 

Pull a glass pipette tip (10 pL Drummond Microdispenser 100 replacement tubes, Broomall, PA, Cat. 3-000-210-G) using a one-stage magnetic puller with a heating element. 

Attach the glass pipette to a microdispenser (10 pL digital, Drummond, Broomall, PA, Cat. 3-000-510-X), and mount the microdispenser onto a micromanipulator. 

There are, of course, noncontact printing devices useful for the construction of microarrays (see Figure 4.2). These are microdispensers that eject droplets by several different mechanisms (solenoid, piezoelectric, heated jet, acoustical wave). Perhaps the best-known commercial dispensers are the syringe driven-solenoid pump (e.g., Cartesian BioDot) and piezo systems (e.g., Packard Biosciences). 

T. Miliotis, S. Kjellstrom, J. Nilsson, T. Laurell, L. E. Edholm, and G. Marko-Varga, Capillary liquid chromatography interfaced to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using an on-line coupled piezoelectric flow-through microdispenser, J. Mass Spectrom., 35 (2000) 369-377. 

For microchemical work there is quite a variety of automatic or semiautomatic buret available. The Schellbach and Squibb types which have already been described have been adapted to microdispensing. These... 

Microreactors for multiple parallel reactions, either fast or long Semi-batch systems similar to titer-plates connected to microdispensing systems and separation/analysis units... 

Scheme4.88 Microfluidic system for MALDI protein analysis, (a) automated sample pretreatment and injection (b) microreactor (c) microdispenser used to deposit sample into nanovials (d) shallow nanovials on the MALDI target plate and (e) automated MALDI-ToF-MS analysis. Reprinted with permission from [345]. Copyright 2000 American Chemical Society.

Figure 6.29 Details of a reagent delivery manifold in an inkjet microdispenser.

Figure 8.8. Flow-through microdispenser addition to a levitated droplet. The dispenser trajectory is seen as the thin white line connecting the dispenser nozzle with the levitated droplet. (Reproduced with permission of Springer-Verlag, Ref. [68].)...

One advantage of micropumps and flow-through microdispensers is that droplet evaporation can be controlled accurately by adding a solvent in order to keep the droplet volume constant, whioh is essential for quantification purposes. Because US increases the temperature of the medium, it can facilitate solvent evaporation. This requires using a system such as an imaging detector to continuously monitor the droplet volume in order to determine the evaporation rate during acoustic levitation. Both mioropumps and microdispensers oan be coupled via FI manifolds to other units for the development of different steps of the analytical process. 

Leopoid et al. reported a system for on-iine monitoring of chemicai reactions in uitra-sonicaiiy ievitated, nanoiitre-sized dropiets by Raman spectroscopy consisting of a fiow-through microdispenser connected to an automated fiow injection system which enabied on-iine coupiing to other steps of the anaiyticai process [113]. 

J. Niisson, J. Bergkvist, S. Ekstrom, L. Waiiman and T. Laureii, Compound Microdispensing, in J. M. Ramsey and A. Van Den Berg (Eds.), Micro Total Analysis Systems 2001, Kiuwer Academic Pubiishers, Monterrey, CA, 2001. 

The method used for application of sample solutions is determined by whether HPTLC, TLC, or preparative layer chromatography (PLC) and qualitative or quantitative analysis are being performed. Sample volumes of 0.5-5 pi for TLC and 0.1-1 pi for HPTLC are applied manually to the layer origin as spots using fixed volume glass micropipets, such as Drummond Microcaps or selectable volume 10 or 25 pi digital microdispensers. In addition, many manual and automated instruments are available for sample application, especially for quantitative HPTLC. 

Yeo, Y. Chen, A.U. Basaran, O.A. Park, K. Solvent exchange method a novel microencapsulation technique using dual microdispensers. Pharm. Res. 2004, 21 (8), 1419-1427. 

The currently most frequently applied method for LC-MALDI-MS is automated post-column fractionation and on-plate collection in discrete spots of the LC colunm effluent. After the solvent is evaporated, the matrix solution can be added, and MALDI-MS analysis of the various spots can be performed. The procedure requires a liquid-handling robot, capable of disposition of effluent fractions at discrete spots on the MALDI target. A number of ways were proposed for deposition in discrete spots on the MALDI target, e.g., blotting via direct contact between droplet and target [139-140], piezoelectric flow-through microdispensing [141], pulsed electrical-mediated droplet deposition [142], and a heated droplet interface [143], Commercial LC-MALDI-MS devices were recently reviewed [144],... 

AV Lemmo, JT Fisher, HM Geysen, DJ Rose. Characterization of an inkjet chemical microdispenser for combinatorial library synthesis. Anal Chem 69 543-551, 1997. 

The format and the preparation of protein microarrays depends on the nature of the immobilised biomolecule and its application. While peptide arrays are manufactured synthetically directly on the support [14], proteins are delivered using either pin-based spotting or liquid microdispensing. To date, the most com-... 

Microdispenser and tubes. No. 6210 1 to 10 pL, 1 to 25 pL, No. 6225 Power supply. No. 1520 Rack, plate holder Rotator, serological Sponge wicks Ziptrol and tubes. No. 6009... 

Apply 2 pL of the control to wells labeled "C" (Figure E40-3) using a microdispenser or Ziptrol. Take care not to damage the wells during sample application. 

Eddington DT, Beebe DJ (2004b) A valved responsive hydrogel microdispensing device with integrated pressure source. J Microelectoromech Sys 13 586-593 Feil H, Bae Y, Feijen J, Kim S (1991) Molecuar separation by thermosensitive hydrogel membranes. J Membr Sci 64 283-294... 

The process for the thennal sensor network is as follows. Organic diodes, to be used as sheet-type thermal sensors, are manufactured on an ITO-coated PEN film. A 30-mn thick p-type semiconductor of copper phthalocyanine (CuPc) and a 50-nm thick n-type semiconductor of 3,4,9,10-perylene-tetracarboxylic-diimide (PTCDI) are deposited by vacuum sublimation. A 150-mn thick gold film is then deposited to form cathode electrodes having an area of 0.19 mm. The film with the organic diodes is coated with a 2-pm thick parylene layer and the electronic interconnections are made by the method similar to that mentioned before. The diode film is also mechanically processed to form net-shaped structures. Finally, to complete the thermal sensor network, we laminated the transistor and diode net films together with silver paste patterned by a microdispenser. This is shown in Figure 6.3.11. 

The solvent elimination approach is better than the one above as full spectral information from the analytes can be obtained and the chromatographic conditions do not have to be modified as much. In practice, the elnting compounds are deposited onto potassium bromide pellets, the mobile phase is evaporated and the pellets are then transferred to the FTIR for spectral analysis by diffuse reflectance. Hence the solvents nsed in the mobile phase must be more volatile than the analytes being smdied. A microdispenser for interfacing LC to IR or Raman which uses the solvent elimination approach has been reported . 

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