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chapter 7: a COMPARISON OF miniaturization TECHNIQUES: top-down and bottom-up manufacturing
7.1 (i) Immunosensors are based upon the specific binding of antibodies with antigens. Describe an ELISA with the aid of diagrams.
(ii) Explain how nonspecific binding can produce unwanted signals. (Nonspecific binding refers to the binding of adsorption of molecules onto the surface without any preference or selectivity.)
7.2. (i) State Moore's law (we are talking about Moore, Intel's cofounder).
(ii) Briefly comment on the significance, validity, and limits of Moore's law for the computer industry.
7.3 How small is small? There are many manufacturing processes other than silicon micromachining for making small parts. Do some research to find specifications for the manufacturing processes listed under problem 7.5. Search the web, call companies, use the yellow pages, use a Thomas's register, ask a machinist, ask your instructor, etc. We're looking for the lower limits on traditional machining or tools that might be currently commercially available at a local job shop, or a tool distributor. The objective is to get a feel for the boundary between MEMS and traditional machining.
7.4 Get calibrated: How many thousandths of an inch (thou or mil) are there in an mm? How many microns in a thou? How many silicon basis cells in a micron? In a cubic micron? Approximately how thick is a human hair? Approximately how big is a virus? A bacteria? A red blood cell? "Exactly" (within a few microns) how thick is a standard sheet of paper (show any calculations)? "Exactly" how big is a pixel on a 600 dpi printer (show any calculations)? Compare the relative resolutions of a printed page and a 5 mmX5 mm micromachined chip.
7.5 Get calibrated. On the Internet, find the answers to the following questions:
Lathe: smallest hole you can drill and smallest repeatable run-out
Milling machine: diameter of the smallest end-mill and drill bit available, resolution of the X-Y stage
Disco saw: smallest cut that can be made
Stamping: smallest line-width and thickness that can be stamped
Punching: smallest punch diameter available
Chemically etched parts: smallest line-width and space
Waterjet cutting: smallest hole and smallest kerf (width of a cut)
Ink-jet printing: smallest dot size
Ultrasonic milling: smallest hold and smallest kerf
Diamond turning: same as for lathe
EDM: smallest hole and smallest slot
Laser machining: smallest hole and smallest kerf
Printed circuit boards: minimum line-width and space
Offset printing: minimum line-width and space
Chemo-mechanical polishing: minimum removable thickness, maximum achievable flatness
Electroplating: minimum RMS roughness
Injection molding: best tolerance for different materials
Silk-screening: minimum line-width and space, film thickness
Stereolithography: smallest solid that can be made, smallest line-width and space
Smallest watch gear: diameter, thickness
Smallest screw: diameter
Smallest DC motor: diameter and length, stall torque, and no-load speed for rated voltage
Best resolution on a pair of calipers
Best resolution with a micrometer
7.6 Immunosensors are based upon the specific binding of antibodies with antigens. With the aid of diagrams, describe
(i) a competitive assay.
(ii) a sandwich assay.
7.7 Nanotechnology: hype or reality (write 1 page)?
7.8 Give a history of mankind’s manufacturing methods. Major events, dates, and examples.
7.9 Compare laser-machining with e-beam machining. Provide the newest data and references.
7.10 Add data points to the Taniguchi and Moore graphs (Figure 7.2) and use examples to illustrate. Provide recent references.
7.11 Rework Figure 7.1 in detail; with examples illustrate absolute size and absolute and relative tolerances. Provide new references and explain.
7.12 Give 4 examples of nanochemistry (bottom-up) achievements, and explain the promises and problems associated with this approach.
7.13 Precision machining is defined at a relative tolerance of ------- or less of a feature/part size and covers both -------- and ----------- processes.
7.14 What are the underlying reasons that both Taniguchi and Moore curves have started showing signs of a slowdown in progress of manufacturing accuracy and of transistor density over time, respectively?
7.15 The followings are examples of micromaching tools.
?8 photofabrication,
?8 laser beam machining,
?8 diamond milling,
?8 chemical and electrochemical milling,
?8 electron beam machining,
?8 photochemical milling,
?8 dry etching,
?8 ultrasonic machining,
?8 plasma beam machining
?8 abrasive jet machining,
?8 electroplating and electroless plating,
?8 stereolithography,
?8 electrodischarge machining
(i) Classify them according to the applied energy appearance (W: wet chemical and electrochemical machining; M: mechanical machining; E: electro-thermal machining) at the workpiece.
(ii) Classify them according to machining methods (S: subtractive; A: additive; S/A: subtractive and additive)
7.16 Why is chemical and photochemical etching mainly applied for shaping of thin metal foils?
7.17 What are the advantages of electrodischarge wire cutting (EDWC) compared with electrodischarge machining?
7.18 Laser machining has advantages such as multi-use, multi-role, and in situ as well as low-temperature deposition process, rapid prototyping, mold fabrication, and site-specific manufacturing. It also has obvious drawbacks. What are they?
7.19 Why is ultrasonic machining suitable for hard and brittle workpieces?
7.20 Why are living systems on first glance violating the Second Law of Thermodyamics?
7.21 Briefly discuss the "who was on first" dilemma: DNA, RNA, or proteins?
7.22 What models are complexity and communication sciences contributing to the biogenesis question?
7.23 Draw a diagram to illustrate how proteins are manufactured.