Techniques discussed in class: Photolithography E-beam lithography Soft lithogra

Question

Techniques discussed in class: Photolithography E-beam lithography Soft lithography: stamp fabrication Soft lithography: microcontact printing Soft lithography: wetting and nucleation AFM lithography ay Which lithographie mecthods are capable of making surface features smaller than 100 nm? b) Suggest a few techniques for making protein patterns on surfaces. c Which method is slower: e-beam lithography or photolithography and why? d) Which techniques can be used for making microfluidic channels in PDMS? e) Discuss the advantages or disadvantages in using conventional polymer 3D printing vs two-photon photopolymerization for making of 3D structures in the range of 100 nm -1

Explanation / Answer

a). Nanofabrication utilizes principles similar to those of microfabrication for the generation of patterns or devices at the nanoscale level, ie, of sizes ranging from 1 to 100 nm.

b).
1. two-dimensional protein patterning using conventional photolithographic methods
2. Three-dimensional microfluidic systems
3. Photochemistry
4. Self-assembled monolayers

c). The smaller field of electron beam writing makes for very slow pattern generation compared with photolithography (the current standard) because more exposure fields must be scanned to form the final pattern area (?mm2 for electron beam vs. ?40 mm2 for an optical mask projection scanner)

d). characterization of a microfluidic packaging technique are used in microfludic channels in PDMS.

e).
e1). Advantage of using conventional polymer 3D printing Vs two photon photopolymerization
1. Polymer 3D printing has advantage that translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data,
2. It builds objects layer by layer without the need for molds or machining.
3. It enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet.
4. Two-photon polymerization (2PP) is an attractive technique for the fabrication of arbitrary three-dimensional structures with feature sizes down to 100 nm.

e2). Disadvantage of using conventional polymer 3D printing Vs two photon photopolymerization
1. The disadvantage of polymer 3D printing is to decrease in manufacturing jobs will greatly affect the economy of countries that rely on a large number of low skill jobs.
2. The size of objects created with 3d printers is currently limited however, in the near future; large items such as architectural structures can be created using 3d printing..
3. Major drawback of conventional microscope objectives (two Photon photopolymerization) is that the limited working distance which is usually around 100 µm.

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