Photochemical Micromachining of Lysozyme Crystals

Abstract

What this work demonstrates is that it is possible to supply power to devices fabricated on silicon that are moved out of the plane of the wafer using polymer actuators. (Of course, this technology is not limited to silicon, but can be used with glass, quartz, or other substrates.) The possible applications are exciting, because so many different kinds of electronic, optical, and micromechanical devices can be produced on silicon. One can envision moving light-emitting diodes or semiconductor lasers, for example, or a comb-drive microgripper being moved into position to grasp a small object.A particular application we are pursuing is a chip for the study of living cells or single-celled organisms. A cavity etched in silicon with a sealable lid could be used to capture a cell, and both the cavity floor and the lid could carry devices for measuring a property of interest. For example, there could be electrodes on them so that the resistance could be measured or a potential applied. Alternatively, a light source on the lid could be coupled with a light detector on the floor for optical measurements. Chemical sensors could monitor the response of the cell. A wafer could be covered with thousands of these devices so that information could be gathered from a great many cells. The devices presented in this paper are one step on the way to such goals. The 3000 thick Al layer was sputtered in an Ar flow of 20 L/min at a pressure of 2 mtorr using a voltage of 380 V (a current of 360 mA) for 20±25 min. The RIE parameters were: 10 sccm/min CHF 3 , 100 sccm/min SF 6 , and 10 sccm/min O 2 at 250 W and 150 mtorr. [32] The following conditions were used: 293 sccm/min He, 968 sccm/min N 2 O, and 57 sccm/min SiH 4 at 21 W and 900 mtorr; substrate heated to 350 C; 40 min. [33] A 30 thick adhesion layer of Cr followed by a 1000 layer of Au; pressure <10 ±6 torr, 4±5 /s deposition rate for Au.

Size effects of solvent molecules on the phase behavior and effective interaction of colloidal systems with the bridging attraction

“…Colloidal systems exist in various products in our daily life, such as shampoo, detergent, paint, food, microemulsions [1], therapeutic drugs [2], and biological systems [3][4][5]. One of the widely studied model systems is the depletion attraction system where there is no attraction between the added small polymers (or small colloidal particles) and the large solute colloidal particles [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Two-Dimensional Nanoparticle Arrays Derived from Ferritin Monolayers

“…The protein molecules are self-assembled into a two-dimensional hexagonally ordered structure from an aqueous solution by the liquid convection due to evaporation. Such thin bioinorganic composite films could find applications as microengineered catalysts and electrocatalysts, robust biosensor architectures, and molecular electronic − and nanoelectronic devices …”

Growth of crystals in optical tweezers

“…Simple polymers, such as polyethylene oxide, with a molecular weight of 1 x 10 6 , has a radius of gyration large enough to be manipulated, and large globular proteins, such as earthworm hemoglobin (30 nm) are also candidates for direct trapping. Lysozyme (1.5nm), when complexed with fluorophores, has been aggregated in the presence of an optical beam 14 .…”