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Fluid Logic Chips
Doc Ruby writes "Colorado researchers 'have constructed microfluidic gates that use the relative flow resistance of liquid to carry out the basic logic operations NOT, AND, OR, XOR, NOR and NAND. The researchers have also combined a pair of gates into a half adder, which carries out half the operation of addition.' All CPUs processing binary logic are made of these types of gates, but usually execute as flows of electrons in wires, not fluids in tubes. Will this advance revolutionize chemistry and computing the way electric gates revolutionized electronics and computing? Will 'fluid programmers' give new meaning to "flowchart"?"
Many years ago (about 1972), Corning and others made "fluidics" devices that used air to implement simple nand gates. They were looking for applications, such as explosive environments (fireworks factories, cotton processing) that relays wouldn't work well in. The devices had simple sensors and could implement logic by combining nand gates. There were a couple of competitors that made fluidic devices. The Corning were small black cans about 2" high and 1/2 around; the air supply was connected on the top and there were 4-inputs and one output on the bottom.
Cute, but they went no where. I put together a neat high school science fair project with them and got to the county level.
Nice to see the concept recycled.
This seems to be a common misperception on slashdot.
Electrons are certainly used, of course, in digital logic circuits. For example representing bits as charge stored in a capacitor, or by mediating the quantum statistics of a transistor for switching (by controlling the charge on the gate of a MOSFET).
However - when a signal is sent down a wire (eg, from a microprocessor, over the data bus, to a peripheral) that signal is NOT being sent through the electron drift. [Although electrons will drift in presence of an electric field, the drift velocity is INCREDIBLY small, look it up.]
If the microprocessor wants to flip a bit from a 0 to a 1, the wire is originally at one potential, and the microprocessor will change the potential. This disturbance isn't instantaneous along the wire, that would violate relativity. The microprocessor basically creates an electromagnetic disturbance that travels down the wire to the peripheral.
Now let's look at this 'disturbance' more closely. Electrons at point A are being ultimately effected by electrons at point B. This effect is mediated through electron interactions, and one knows that that the electromagnetic force is the mediator between electrons. And from Quantum Field Theory one knows that photons are the quanta of the electromagnetic force.
So what this in effect means is that whenever electrons are interacting, photons are being transmitted somewhere during that exchange. Thus, the parent was correct that it's the electromagnetic wave, as opposed to the physical motion of the electrons themselves. that plays the role in limiting digital logic speed.
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