Abstract: This invention relates to a systems and methods of controlling the flow of a fluid in a capillary or microfluidic channel. A first pair of electrodes can influence the wetting of a fluid front at a relatively hydrophobic surface in the channel. A second pair of electrodes can electrolytically generate a bubble that can stop fluid flow when it contacts the hydrophobic surface. Flow of a fluid in a channel can be stopped on contact with the hydrophobic surface and restarted when an electrostatic field reduces the contact angle of the fluid at the hydrophobic surface. The electrostatic field can be removed and the fluid stopped again when an electrolytically generated bubble contacts the hydrophobic surface to reestablish the blocking contact angle of the fluid, gas and surface.

Abstract: This invention relates to a systems and methods of controlling the flow of a fluid in a capillary or microfluidic channel. A first pair of electrodes can influence the wetting of a fluid front at a relatively hydrophobic surface in the channel. A second pair of electrodes can electrolytically generate a bubble that can stop fluid flow when it contacts the hydrophobic surface. Flow of a fluid in a channel can be stopped on contact with the hydrophobic surface and restarted when an electrostatic field reduces the contact angle of the fluid at the hydrophobic surface. The electrostatic field can be removed and the fluid stopped again when an electrolytically generated bubble contacts the hydrophobic surface to reestablish the blocking contact angle of the fluid, gas and surface.

Abstract: This invention relates to a micromachined capacitive microphone having a shallowly corrugated diaphragm that is anchored at one or more locations on the support has a plurality of dimples to support itself and rest freely on the perforated backplate. The diaphragm whose ends are not anchored is bounded by the taps of edge rail. Also disclosed includes: a fixed perforated backplate having one or more regions; an adjustable cantilever formed by the diaphragm, the support and the backplate; a plurality of dimples maintaining vertical separation between diaphragm and backplate; and the patterning of conductor electrodes carried by diaphragm and backplate.

Abstract: An adaptive alignment technique provides precise control and active positioning in, preferably, two-dimensions of sub-millimeter-sized objects such as, in one application, spherical mircolenses through the application of electrophoretic forces in a microfluidic wells. A lithographically patterned microfluidic well and electrodes can be addressed to position or align a spherical microlens to a corresponding laser light beam. The motion of the microlens is preferably controlled using CMOS compatible voltages (3V–1 ?A) that are preferably applied to opposite electrodes in the microfluidic well, creating an electrical field in a well solution. By applying voltages to opposed electrode pairs, movement of spherical microlenses with sizes ranging from, most typically, 0.87 ?m to 40 ?m in directions parallel to the electrode surface is realized. Under a bias of 3 volts, the microspheres have electrophoretic velocities ranging from 13 to 16 ?m/s.

Abstract: Small particles, for example 5 ?m diameter microspheres or cells, within, and moving with, a fluid, normally water, that is flowing within microfluidic channels within a radiation-transparent substrate, typically molded PDMS clear plastic, are selectively manipulated, normally by being pushed with optical pressure forces, with laser light, preferably as arises from VCSELs operating in Laguerre-Gaussian mode, at branching junctions in the microfluidic channels so as to enter into selected downstream branches, thereby realizing particle switching and sorting, including in parallel. Transport of the small particles thus transpires by microfluidics while manipulation in the manner of optical tweezers arises either from pushing due to optical scattering force, or from pulling due to an attractive optical gradient force. Whether pushed or pulled, the particles within the flowing fluid may be optically sensed, and highly-parallel.

Abstract: An adaptive alignment technique provides precise control and active positioning in, preferably, two-dimensions of sub-millimeter-sized objects such as, in one application, spherical mircolenses through the application of electrophoretic forces in a microfluidic wells. A lithographically patterned microfluidic well and electrodes can be addressed to position or align a spherical microlens to a corresponding laser light beam. The motion of the microlens is preferably controlled using CMOS compatible voltages (3V-1 &mgr;A) that are preferably applied to opposite electrodes in the microfluidic well, creating an electrical field in a well solution. By applying voltages to opposed electrode pairs, movement of spherical microlenses with sizes ranging from, most typically, 0.87 &mgr;m to 40 &mgr;m in directions parallel to the electrode surface is realized. Under a bias of 3 volts, the microspheres have electrophoretic velocities ranging from 13 to 16 &mgr;m/s.