Microfabrication polymerization

Cai K, Luo Z, Hu Y, Chen X, Liao Y, Yang L, Deng L (2009) Magnetically triggered reversible controlled drug delivery from microfabricated polymeric multireservoir devices. Adv Mater 21 4045-4049... 

Cai, K. Luo, Z. Hu, Y Chen, X. Liao, Y Yang, L. Deng, L. Magnetically triggered reversible controlled drug dehvery from microfabricated polymeric multireservoir devices. Adv. Mater. 2009, 21, 4045 1049. 

Cumpston BH, Ananthavel SP, Barlow S, Dyer DL, Ehrlich JE, Erskine LL, Heikal AA, Kuebler SM, Lee IS, McCord-Maughon D, Qin J, Rockel H, Rumi M, Wu XL, Marder SR, Perry JW (1999) Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication. Nature 398 51-54... 

The most effective wavelength for 2P-microfabrication in acrylates depends on the 2PA spectra of the chromophores used as initiators, as the initiation rate is proportional to the 2PA cross section (see Eq. 8). In the case of polymerization of SR9008 by q.2, it was shown that Rp has approximately... 

Organic-silica hybrid materials have been used for multi-photon microfabrication. These include the acrylate-functionalized oligosiloxanes known as ORMOCERs, which have been polymerized by radical processes using conventional IP radical iniatitors, such as c.2 [221,234]. Commercial poly(dimethylsiloxane)-based resists containing vinyl and Si-H functionalities use two different 2PA-induced processes hydrosilylation catalyzed by the photodecomposition products of Cp PtMes (Cp = ti -methylcyclopentadienyl) and radical initiation by c.4 (Fig. 13) [235]. The former process was complicated by thermally-induced polymerization. 

In addition to these examples, an electron-transfer free radical photoinitiator H-Nu 470 (5,7-diiodo-3-butoxy-6-fluorone) has been also successfully used for 3D microfabrication by near-IR two-photon induced polymerization... 

It is noteworthy that nonlinearity of the absorption, required for 3D microfabrication can be provided via thermal mechanisms [53,54]. In the case of tightly focused laser pulses, linear absorption is most efficient at the focus, where local heating can create the conditions required for polymerization. Usually the absorption increases with temperature and thermal polymerization may become dominant at the focus. It is usually difficult to confirm the TPA mechanism from the direct transmission measurements due to the nar-... 

Maruo S, Ikuta K (2000) Three-dimensional microfabrication by use of single-photon-absorbed polymerization. Appl Phys Lett 76 2656-2658... 

Novel microreactors with immobilized enzymes were fabricated using both silicon and polymer-based microfabrication techniques. The effectiveness of these reactors was examined along with their behavior over time. Urease enzyme was successfully incorporated into microchannels of a polymeric matrix of polydimethylsiloxane and through layer-bylayer self-assembly techniques onto silicon. The fabricated microchannels had cross-sectional dimensions ranging from tens to hundreds of micrometers in width and height. The experimental results for continuous-flow microreactors are reported for the conversion of urea to ammonia by urease enzyme. Urea conversions of >90% were observed. 

Only very few studies with alternative materials and fabrication methods have been published. Ekstrom et al. [35] demonstrated the feasibility of structuring inexpensive polymeric materials by means of a microfabricated master for the production of microchannel systems. The structured polymer film was mechanically clamped between two glass plates to form a closed channel system. Recently, a similar route for the fabrication of microchannel chips that relies on casting of an elastomeric polymer material against a microfabricated master has been presented by Effenhauser et al. [36] (see Sect. 3.4). 

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. 

Microfluidics and miniaturization hold great promise in terms of sample throughput advantages [100]. Miniaturization of analytical processes into microchip platforms designed for micro total analytical systems (/i-TASs) is a new and rapidly developing field. For SPE, Yu et al. [123] developed a microfabricated analytical microchip device that uses a porous monolith sorbent with two different surface chemistries. The monolithic porous polymer was prepared by in situ photoinitiated polymerization within the channels of the microfluidic device and used for on-chip SPE. The sorbent was prepared to have both hydrophobic and ionizable surface chemistries. Use of the device for sorption and desorption of various analytes was demonstrated [123]. 

Wang, S.-C., Perso, C.E., Morris, M.D., Effects of alkaline hydrolysis and dynamic coating on the electroosmotic flow in polymeric microfabricated channels. Anal. Chem. 2000, 72(7), 1704-1706. 

Slentz, B.E., Penner, N.A., Regnier, F.E., Capillary electrochromatography of peptides on microfabricated poly(dimethylsiloxane) chips modified by cerium(IV)-catalyzed polymerization. J. Chromatogr. A 2002, 948, 225-233. 

Numerous microfabrication techniques have been used to produce a wide range of implantable and oral drug delivery systems using materials ranging from silicon, glass, silicone elastomer, and plastics. Fabrication techniques have rapidly evolved to produce nanoscale objects and therapeutic systems using polymeric materials as the substrate due to their biodegradable nature. There are a number of different synthetic polymer systems that have been developed for this type of application, and the most common ones are listed below ... 

Membranes fabricated using the MEMS technology are finding an increasing number of applications in sensors, actuators, and other sophisticated electronic device. However, the new area of application of MEMS is creating new materials demands that traditional silicon cannot fulfill [43]. Polymeric materials, also in this case, are the optimal solution for many applications. Microfabrication of polymeric films with specific transport properties, or micromembranes, already exists, and much work is in progress [44-50]. 

The use of TP initiated polymerization for 3D microfabrication has several advantages over OP initiated polymerization. A 3D resolution can be achieved with lateral and depth resolutions of 0.2 pm and 0.28 pm. This is fabrication at a... 

Figure 3.71. Optical system used for 3D microfabrication using TP initiated polymerization of a photopolymerizable composition. The numerical aperture of the objective lens is 0.85 (magnification of 40), the accuracy of the galvano-scanner set and the dc motor scanner were 0.3 and 0.5 pm, the beam power at peak in the photocrosslinkahle composition is about 3 kW, with a repetition rate of 76 MHz and a pulse width of 130 fs at a wavelength of 770 nm [76].

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