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Pdms scaffold meaning12/24/2023 In order to avoid the use of silicon masters and (clean room) lithography, and the subsequent bonding of PDMS to another surface or the complex fabrication of sacrificial molds, we propose the use of an off-the-shelf plastic polymer, used for 3D printing, as scaffold for creating micrometric sized channels. We baptize this methodology ESCARGOT: Embedded SCAffold RemovinG Open Technology. Using the ABS scaffold-removal method, there is no need of lithography steps nor silicon masters, no need of bonding the PDMS on surfaces nor of repetitive procedures for obtaining multilevel channels, making the fabrication of microfluidic devices easy, low-cost and opening up the field for a plethora of scientists working in different areas. A most striking example is the fabrication of a high-resolution nuclear magnetic resonance device that provides molecular analysis of just microliter volumes. We also show how, using the scaffold-removal fabrication method, external components, such as heating elements, electronics or RF circuitry, can be embedded directly in microfluidic devices. Here we present an easy two-step acrylonitrile butadiene styrene (ABS) scaffold-removal method for achieving 3D, multilayer, intricate, micrometric channels in a single block of PDMS. Moreover, embedding other functionalities as described in this research, is extremely hard or even impossible using a 3D printer for directly printing a microfluidic chip. 28 PDMS is usually preferred over other 3D printing plastics because of a) its gas permeability, useful in biology for keeping cells and bacteria alive for long time in the microfluidic chip b) its elasticity, capable of making micro pumps and valves in the device and c) its simple chemical modification using well known silane chemistry, difficult thing to do on 3D printing plastics and d) its transparency. The limitation of 3D printing directly the microfluidic devices lies mainly in the material used and, so far only one example of 3D printed PDMS membrane is present in literature with the limitation of using PDMS mixed with colored photoresist, thus not pure PDMS and giving non transparent devices. 25- 27 In the first case, although the mold is easily printed, it has the same limitation for creating multilayer and complex microfluidic devices than the standard clean room lithography. Recently, 3D printing has been used either to print masters for soft lithography mold, 24 or to directly print microfluidic devices. Although the use of sacrificial mold is a step forward in simplifying the fabrication of microfluidic devices, it still requires either harsh condition like the use of high temperatures for creating, 18 or removing, 19 a template, applying heavy swelling for pulling out the template, 20, 21 or the use of complex mold fabrication such as using chitosan 22 or isomalt printed with an heavily modified 3D printer and backfilled with epoxy resin. 17 In recent years, sacrificial mold or fugitive ink is used for fabricating PDMS microfluidic devices. 9 Second, achieving a 3D (multilevel channels or a single channel with different sizes) using standard fabrication methods is rather complicated, as multiple layers of PDMS must be fabricated and then sealed together to create an internal 3D channel. First, the PDMS fabrication method is considered too complex for many scientists without any experience in microfabrication. Notwithstanding the great potential, two main bottlenecks inhibit a more widespread use of PDMS devices. Consecutively, PDMS is poured on the master, and after curing, the rubber must be carefully peeled off from the master and subsequently chemically bonded to another surface after activation with oxygen plasma or using chemical solutions. For the manufacturing of microfluidic PDMS devices, generally a master is needed, usually obtained by clean-room lithography of silicon wafers. 14- 16 It is relatively cheap and easy to manipulate, gas permeable and has a refractive index of 1.4, close to the one of glass. 13 To date, polydimethylsiloxane (PDMS) is the most popular material in research laboratories for the fabrication of microfluidic devices. ![]() 12 The small amounts of liquid required for experiments, the physics of fluids at the micro domain and the lab-on-chip approach make microfluidics one of the interdisciplinary field par excellence. Microfluidics 1, 2 is a continuously growing field, of great interest in chemistry, 3 physics, 4, 5 drug discovery, 6 biology, 7, 8 chemical biology, 9 biomedical research, 10 tissue engineering, 11 and most recently, organs-on-chip.
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