Micro-electrochemical valves and method
First Claim
1. A microelectrochemical valve structure comprising:
- a monolithic substrate having a pair of opposed major surfaces;
an array of passages through said substrate, each of said passages extending between and connecting said major surfaces, each of said passages further having a size defined by its minimum cross-sectional area;
an electrochemically removable barrier associated with each of said passages in a position blocking fluid flow through said passage;
an electrode associated with each of said passages, said electrode being in contact with said passage barrier, said electrode further being in electrical communication with an external lead; and
at least one counter electrode associated with one of said substrate major surfaces, said counter electrode being in electrical communication with an external lead, said counter electrode further having the property of being in electrical communication with said passage electrodes when said associated substrate surface is in contact with an electrolyte,wherein a voltage difference applied between said counter electrode lead and one of said passage electrode leads removes the barrier associated with said passage thereby increasing flow communication between said substrate surfaces by an amount proportional to said passage'"'"'s size.
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Abstract
A micromachined valve and valve array having one or more pores which are electrochemically opened and closed by dissolving and redepositing a barrier layer across a tiny opening or pore in substrate. The pore is spanned by two electrodes which apply a voltage to an electrolytic barrier layer material which dissolves in an electrolyte. Each open pore has a distinct flow rate related to its minimal cross-sectional area which together can form a binary sized array with each subsequent member in the array having a flow rate twice as large as the preceding member in the array. Any integral multiple of the smallest flow rate may be achieved by opening an appropriate combination of the pores with addressing logic. In a preferred embodiment, each bit in a binary representation of the desired flow rate acts as a switch for a pore having a flow rate corresponding to the bit position.
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Citations
17 Claims
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1. A microelectrochemical valve structure comprising:
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a monolithic substrate having a pair of opposed major surfaces; an array of passages through said substrate, each of said passages extending between and connecting said major surfaces, each of said passages further having a size defined by its minimum cross-sectional area; an electrochemically removable barrier associated with each of said passages in a position blocking fluid flow through said passage; an electrode associated with each of said passages, said electrode being in contact with said passage barrier, said electrode further being in electrical communication with an external lead; and at least one counter electrode associated with one of said substrate major surfaces, said counter electrode being in electrical communication with an external lead, said counter electrode further having the property of being in electrical communication with said passage electrodes when said associated substrate surface is in contact with an electrolyte, wherein a voltage difference applied between said counter electrode lead and one of said passage electrode leads removes the barrier associated with said passage thereby increasing flow communication between said substrate surfaces by an amount proportional to said passage'"'"'s size. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for producing quantitatively variable flow communication between major surfaces of a monolithic substrate comprising:
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forming a series of n passages through said substrate, each of said passages having a different size defined by its minimum cross-sectional area, said series being characterized by the first member in said series having the smallest size with each subsequent member in said series having a size twice as large as the previous member such that the nth member of said series has a size 2.sup.(n-1) times the size of the first member; positioning a separate electrochemically removable barrier to block flow through each of said passages, each of said barriers being selectively removable; and electrochemically removing said barriers from a selected group of said passages to produce quantitative flow communication between said substrate surfaces. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for producing quantitative variable flow through a monolithic substrate comprising:
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an array of n individually gated passages through said substrate, each of said passages having a different predetermined flow rate fi associated therewith when said passage gate is open, said flow rates being characterized by the relation fi =2.sup.(i-1) ×
f1 for i=1 to n with f1 being the smallest flow rate;input means for expressing a desired flow rate as in n-bit binary numbers; and means for selectively opening the passage through said substrate having flow rate fi when the ith bit in said binary number is a 1. - View Dependent Claims (16, 17)
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Specification