BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 shows a prior art LIMMS;
FIG. 2 shows a first embodiment of an improved LIMMS device;
FIG. 3 shows a second embodiment of an improved LIMMS device; and
FIG. 4 shows a third embodiment an improved LIMMS device.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows prior art LIMMS device 10, comprising channel 100 and inlet 103. Electrical contacts may be at end walls 105a, 105b and 104. Switching material 101 is in two volumes, 101a and 101b, but with bridge volume 101c joining volumes 101a and 101b. Bridge volume 101c exists because actuating force 102, possibly provided by a heated gas from inlet 103, cannot fully split the two volumes 101a and 101b. Because of volume 101c there is electrical continuity in the switch and the switch does not open as discussed above.
FIG. 2 shows LIMMS device 20, arranged according to an embodiment of the invention. Device 20 comprises channel 200, inlet 203, and perturbation 206. Electrical contacts may be at end walls 205a, 205b and 204. Switching material 201 is in two volumes, 201a and 201b. The “notch”, or wall perturbation 206, adjacent to inlet 203, positively influences how actuating force 202 acts on the liquid metal, thereby separating volumes 201a and 201b, unlike what occurred in prior art device 10, as shown in FIG. 1. Notch 206 forces the heated gas bubble to remain more contained near inlet 203, because the surface tension of the liquid and contact angle of the liquid will not allow the heated gas bubble to grow beyond the notch. In one embodiment, notch 206 forms a 90° contact angle with the walls of bubble 202. This localization of the heated gas bubble makes it easier for the gas bubble to span across the channel thereby splitting the liquid into volumes 201a and 201b.
Actuating force 202 may be provided by heated gas available at inlet 203. Inlet 203 could provide a reservoir for the gas, such that when the gas is unheated it is at pressure equilibrium, and will not try to do work on the liquid in channel 200. Channel 200 may contain linings of non-wettable surfaces 207a, 207b and 207c, with wettable surfaces elsewhere in the channel. The use of non-wettable surfaces 207 near inlet 203, and wettable surfaces elsewhere, assists with breaking the liquid of switching material 201 into separate slugs.
FIG. 2 shows a section of a single-pole, double-throw switch and FIG. 5 shows, in schematic form, an overview of the full switch having heating element 51 which operates to create actuating force 202 which separates liquid metal volume 201a from liquid metal volume 201b. As shown in FIG. 5, heater 52 operates to create an actuating force (not shown because heater 52 is not enabled in FIG. 5) to selectively separate liquid metal volume 501 from liquid metal volume 201b to cut off (when heater 52 is activated) electrical signal flow to terminal 500. Note that when heater 52 is activated and heater 51 is not activated, volumes 201b and 501 will separate and volumes 201b and 201a will reunite so that electrical signals can pass between terminals 205a, 205b and 200, instead of passing between terminals 205a, 205b and 500. However, embodiments of the switch include multi-pole, multi-throw switches as shown, for example, in the above-identified copending application commonly assigned U.S. patent application Ser. No. 11/399,644, Attorney Docket No. 10051238-1, filed on Apr. 6, 2006 entitled “ARCHITECTURE FOR MULTI-THROW MICRO-FLUIDIC DEVICES”.
FIG. 3 shows LIMMS device 30, arranged according to an embodiment of the invention. Device 30 comprises channel 300, inlet 303, and perturbation 306. Electrical contacts may be at end walls 305a, 305b and 304. Switching material 301 is in two volumes, 301a and 301b. Wall perturbation 306, approximately across channel 300 from inlet 303, positively influences how the actuating force 302 acts on the liquid metal, thereby separating volumes 301a and 301b. This perturbation can have any shape or size desired with the goal of narrowing the distance required in the channel to split the liquid into two volumes 301a and 301b.
FIG. 4 shows LIMMS device 40, arranged according to an embodiment of the invention. Device 40 comprises channel 400 and inlets 403a and 403b. Electrical contacts may be at end walls 405a, 405b and 404. Switching material 401 is in two volumes, 401a and 401b. Inlets 403a and 403b each provide actuating force, 402a and 402b, respectively. Each actuating force, 402a or 402b, need only work across approximately half the channel in order to fully separate volumes, 401a and 401b.
In situations where the LIMMS device was required to have high-reliability operation, inlets 403a and 403b could provide redundant operation. That is, in normal operation, inlets 403a and 403b would each insert actuating force into channel 400, as described, for example, with respect to FIG. 2. However, if either inlet 403a or 403b failed, such as would occur, for example, if a gas heating element failed, or in the case that the inlets share a heating element and one inlet becomes clogged, then the remaining operational inlet would continue to provide switching capability. Note that the diversion mechanism can either be a structure (of the type shown in FIGS. 2 and 3) or a force (of the type shown in FIG. 4).
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
Patent Application
20070289853
