Microdroplet technology

Abstract The self-organized and molecularly smooth surface on liquid microdroplets makes them attractive as optical cavities with very high quality factors. This chapter describes the basic theory of optical modes in spherical droplets. The mechanical properties including vibrational excitation are also described, and their implications for microdroplet resonator technology are discussed. Optofluidic implementations of microdroplet resonators are reviewed with emphasis on the basic optomechanical properties. 

Further advances in skin resurfacing technologies, such as the use of gas jets and accelerated microdroplets (JetPeel [62]), may offer additional mechanisms for transporting medicaments through the stratum corneum barrier. 

The gel microdroplet technique is described in articles by Powell KT, Weaver JC (1990). Gel microdroplets and flow cytometry Rapid determination of antibody secretion by individual cells within a cell population. Bio/Technology 8 333 337 and Weaver JC, Bliss JG, Powell KT, et al. (1991). Rapid clonal growth measurements at the single cell level. Bio/ Technology 9 873. 

Fig. 11.12. Reprinted from Weaver JC, et al. (1991). Rapid clonal growth measurements at the single cell level gel microdroplets and flow cytometry. Bio/Technology 9 873.

In the recent past liquid membranes were employed for the separation and extraction of materials, and they can be conveniently employed for separating biological materials [129-137], Microemulsions of Winsor I (o/w) and Winsor II (w/o) types are considered dispersed liquid membranes that can augment the transfer of oil-soluble and water-soluble compounds, respectively, across them by trapping them in microdroplets for convenient uptake and subsequent release. The microemulsions (Winsor I and II) are called bulk liquid membranes. They are recent additions in the field of separation science and technology. This field has been fundamentally explored and advanced by Tondre and coworkers [138-147], who worked out the fundamentals of the transport process by studying the transfer of alkali metal picrates and other compounds across the w/o microemulsions [140-142], They also studied the transport of lipophilic compounds (pyrene, perylene, and anthracene) across o/w liquid membranes [138,139],... 

MacFarlane et al. used microjet (or inkjet) technology to fabricate microlens arrays [23]. Figure 4.27 shows the setup to generate microdroplets. The microjet system consisted of a piezoelectric ceramic with a microchannel. A nozzle exit was aligned at one end of the channel and a capillary tube intake connected to a reservoir was fitted at the other end. The reservoir was heated to lower the viscosity of the jetted polymer materials. 

Polymer-dispersed liquid crystals (PDLCs) are important to liquid-crystal technology. Nematic LC microdroplets are dispersed in a polymer matrix. These films are used similarly to liquid crystal displays such as displays, switchable windows, and light shutters. PDLC devices operate on the principle of electrical modulation of the LC refractive index to match or mismatch the refractive index of an optically transparent, isotropic solid. PDLC films are made between conductive, transparent substrates, and can be switched from being opaque to being transparent with the application of an electric field. Solid state NMR methods have been used to study (PCLCs) and to identify the LC/polymer interface [80,81]. Using NMR one can iden-... 

S.J. Eichom and R.J. Young, Composite micromechanics of hemp fibax and epoxy resin microdroplets. Composites Science and Technology, 2004, 64, p. 767 - 772... 

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