Micromachined fluid analysis device and method

A micromachined filtering device comprising at least two substrates in fluidic series, each of the substrates having a first surface, an oppositely-disposed second surface, a thickness defined by and between the first and second surfaces thereof, a plurality of vias through the thickness thereof, and first and second electrodes on the first surface thereof, wherein:

• the vias of the first substrate are spaced apart and have approximately equal first diameters that prevent passage through the first substrate of a first material having a diametrical dimension greater than the first diameters and permit passage through the first substrate of a second material having a diametrical dimension less than the first diameters;
• the first and second electrodes of the first substrate are located on the first surface thereof so that the first material that collects at the first surface of the first substrate will electrically connect the first and second electrodes of the first substrate to produce a first output signal in proportion to the amount of the first material collected at the first surface of the first substrate;
• the vias of the second substrate are spaced apart and have approximately equal second diameters that are smaller than the first diameters of the first substrate and that prevent passage through the second substrate by the second material as a result of the second material having a diametrical dimension greater than the second diameters;
• and
• the first and second electrodes of the second substrate are located on the first surface thereof so that the second material that collects at the first surface of the second substrate will electrically connect the first and second electrodes of the second substrate to produce a second output signal in proportion to the amount of the second material collected at the first surface of the second substrate.

A method of filtering a fluid with a micromachined filtering device comprising at least two substrates in a fluidic series, the fluid containing a first material having a first diametrical dimension and a second material having a second diametrical dimension that is less than the first diametrical dimension, the method comprising the steps of:

• flowing the fluid through vias in a first of the at least two substrates, the first substrate having a first surface, an oppositely-disposed second surface, and a thickness defined by and between the first and second surfaces, the vias extending through the thickness of the first substrate and having approximately equal diameters that permit passage through the first substrate by the second material and that prevent passage through the first substrate by the first material;
• sensing the amount of the first material that collects at the first surface of the first substrate with first and second electrodes located on the first surface so that the first material electrically connects the first and second electrodes to produce a first output signal in proportion to the amount of the first material collected at the first surface;
• after the fluid has flowed through the first substrate, flowing the fluid through vias in a second of the at least two substrates, the second substrate having a first surface, an oppositely-disposed second surface, and a thickness defined by and between the first and second surfaces, the vias extending through the thickness of the second substrate and having approximately equal diameters that prevent passage through the second substrate by the second material;
• and sensing the amount of the second material that collects at the first surface of the second substrate with first and second electrodes located on the first surface so that the second material electrically connects the first and second electrodes to produce a second output signal in proportion to the amount of the second material collected at the first surface.