Electrothermal branding for embryo labeling
A novel embryo labeling technique based on electrothermal branding is developed. Two types of micro branding irons are fabricated and tested. One utilizes 25 /spl mu/m tungsten wire as the heating element. The other utilizes surface micromachining techniques to fabricate polysilicon branding irons. The thermal behavior of the branding irons and the heat distributions in the embryos are analytically modeled. Micron-scale labels on unfertilized bovine embryos are achieved.
Handling individual mammalian embryos using microfluidics
We have designed, built, and tested microfluidic systems capable of transporting individual, preimplantation mouse embryos (100-/spl mu/m m to 150-/spl mu/m diameter) through a network of channels. Typical channels are 160 to 200 /spl mu/m deep, 250 to 400 /spl mu/m wide at the top, and narrower at the bottom (0 to 250 /spl mu/m wide) due to the fabrication process. In these channels, a pressure gradient of 1 Pa/mm causes the medium to flow on the order of 10/sup -10/ m/sup 3//s (100 nl/s), with an average speed of 1 to 2 mm/s. Under these flow conditions the embryos roll along the bottoms of the channels, traveling at 1/2 the speed of the fluid. By manipulating the pressure at the wells connected to the ends of the channels, the embryos can be transported to (and retained at) specific locations including culture compartments and retrieval wells.
Microwave diathermy: the invisible healer.
The medical use of heat produced by microwave radiation is called microwave diathermy, which has been the subject of considerable study by FDA over the last few years. The lack of reliable safety controls on many of these machines to prevent possible overexposure of harmful radiation to patients is one of several reasons why the Agency will soon propose a performance standard that will assure the safety and effectiveness of these medical services.