1. A method of fabricating a separation column for use with a gas chromatograph, comprising:
depositing a metal oxide by atomic layer deposition to create a stationary phase medium on said separation column.
2. The method of claim 1 wherein said metal oxide is aluminum oxide.
3. The method of claim 3 wherein said aluminum oxide is deposited as a plurality of layers with each layer deposited in a cycle comprising (a) exposure to trimethylaluminum (b) purge (c) exposure to water (d) and purge.
4. The method of claim 3 wherein each cycle deposits a layer of about 1-2 angstroms.
5. The method of claim 2 wherein said aluminum oxide is functionalized by exposure to silane.
6. The method of claim 5 wherein said silane is an alkylsilane.
7. The method of claim 6 wherein said silane is chlorodimethyloctadecylsilane.
8. The method of claim 2 wherein said aluminum oxide is functionalized by exposure to a plurality of silanes.
9. A detector comprising:
a micro-purge extractor in communication with a micro-scale gas chromatography column for the extraction and analysis of water organic compounds from an aqueous sample;
said micro-purge extractor having a cavity in communication with a sample inlet port, a purge gas inlet port, a waste outlet port and a purged water organic compound outlet port;
said sample inlet port adapted to receive an aqueous sample;
said purge gas inlet port, spaced apart from said sample inlet port, and adapted to receive inert gas which is used to purge water organic compounds from said cavity of said micro-purge extractor;
said waste outlet opposingly located from said purge outlet port, said waste outlet adapted for draining water from the chip;
said purge outlet in communication with a micro-thermal preconcentrator;
said micro-thermal preconcentrator adapted to adsorb and desorb water organic compounds;
at least one resistive heating element that when activated, causes said water organic compounds to be desorbed; and
said micro-scale gas chromatography column adapted to separate said water organic compounds and a micro-thermal conductivity detector for identifying said water organic compounds.
10. The detector of claim 9 wherein said separation column has an aluminum oxide stationary phase medium.
11. The detector of claim 10 wherein said aluminum oxide is functionalized by exposure to silane.
12. The method of claim 11 wherein said silane is an alkylsilane.
13. The method of claim 11 wherein said silane is chlorodimethyloctadecylsilane.
14. The method of claim 10 wherein said aluminum oxide is functionalized by exposure to a plurality of silanes.
15. The detector of claim 9 wherein said purge outlet port and said sample inlet port are located on a top side of said micro-purge extractor, said purge gas inlet is located on a side of said micro-purge extractor, and said waste outlet port is located on a bottom side of said micro-purge extractor.
16. A detector for detecting hazardous air pollutants at parts-per-billion concentrations in complex mixtures comprising:
a microfabricated preconcentrator;
a separation column with an on-chip thermal conductivity detector;
a controller for controlling flow and thermal management; and
a user interface.
17. The detector of claim 16 wherein said thermal conductivity detector includes a first resistor located at an inlet of said separation column and a second resistor located at an outlet of said separation column.
18. The detector of claim 16 wherein said separation column includes a medium comprised of silica a nanoparticle layer with a Tenax TA coating.
19. The detector of claim 16 wherein said separation column includes at least one channel that linearly decreases in width.
20. The detector of claim 16 wherein said separation column includes at least one channel that decreases in width in a stepwise fashion.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A forward-forward converter FFC having a first gapped transformer with a primary winding for receiving electrical energy from a source of electrical power and a secondary winding coupled to said primary winding, said converter also having a power switch for intermittently coupling said transformer to said source of electrical power and a clamp switch for intermittently coupling said transformer to said clamp capacitor, said converter, comprising:
a second gapped transformer, having an input winding coupled to said secondary winding of the first transformer, configured to form an intermediate circuit mesh and extend said zero-voltage switching possibility said converter and output energy transfer, through an output winding coupled to said input winding, during conduction of said clamp switch.
2. The forward-forward converter as recited in claim 1 wherein a reverse current circulating in said intermediate circuit mesh is coupled to said primary winding to achieve zero-voltage switching (ZVS) of said power and clamp switches.
3. The forward-forward converter as recited in claim 2 wherein a reverse current circulates during an interval between non-conducting and conducting periods of said power and clamp switches.
4. The forward-forward converter as recited in claim 2 further to use leakage inductance in said intermediate circuit mesh to provide said reverse current.
5. The forward-forward converter as recited in claim 2 further to use leakage inductance in series with auxiliary inductance in said intermediate circuit mesh to provide said reverse current.
6. The forward-forward converter as recited in claim 1 wherein said primary, secondary and input winding use a same voltage phase, and said output winding uses an opposite voltage phase.
7. The forward-forward converter as recited in claim 1 wherein said primary, secondary and input winding use a same voltage phase, and said output windings use a same and an opposite voltage phase.
8. The forward-forward converter as recited in claim 1 wherein a volt-second requirement for said second transformer is less than said first transformer.
9. The forward-forward converter as recited in claim 1 wherein each of said power and clamp switches employ a MOSFET having parasitic capacitance.
10. A method of conversion energy for use with a forward-forward converter, comprising:
employing a first transformer with a primary winding for receiving electrical energy from a source of electrical power and a secondary winding coupled to said primary winding, said converter also having a power switch for intermittently coupling said transformer to said source of electrical power and a clamp switch for intermittently coupling said transformer to said clamp capacitor, said converter; and
further employing a second transformer, having an input winding coupled to said secondary winding, that forms an intermediate circuit mesh and extend said output energy transfer, through an output winding coupled to said input winding, during conduction of said clamp switch.
11. The method as recited in claim 10 wherein a second transformer, having an input winding coupled to said secondary winding, that forms an intermediate circuit mesh and extend said output energy transfer, through the output windings coupled to said input winding, during conduction of said power and clamp switches.
12. The method as recited in claim 10 wherein a reverse current circulating in said intermediate circuit mesh is coupled to say primary winding and extends zero-voltage switching (ZVS) of said power and clamp switches.
13. The method as recited in claim 10 wherein said reverse current circulates during the intervals between non-conducting and conducting periods of said power and clamp switches.
14. The method as recited in claim 12 further comprising using a leakage inductance in said intermediate circuit mesh to provide said reverse current.
15. The method as recited in claim 12 further comprising using a leakage inductance in series with auxiliary inductance in said intermediate circuit mesh to provide said reverse current.
16. The method as recited in claim 10 wherein said primary, secondary and input windings use a same voltage phase, said output winding uses opposite voltage phase.
17. The method as recited in claim 11 wherein said primary, secondary and input windings use a same voltage phase, said output windings use a same and opposite voltage phase.
18. The method as recited in claim 10 wherein a volt-second requirement for said second transformer is less than said first transformer.
19. The method as recited in claim 10 wherein each of said power and clamp switches uses a MOSFET having a parasitic capacitance.
20. A forward-forward converter (FFC), comprising:
an input voltage a source of electrical power;
power and clamp switches coupled to said input voltage;
a conversion circuit, including:
a first transformer, having a primary winding coupled to said power and clamp switches and a secondary winding coupled to said primary winding that provides an output energy transfer of said forward-forward converter during conduction of said power switch, and
a second transformer, having an input winding coupled to secondary winding, that forms an intermediate circuit mesh and extends said output energy transfer, through an output winding coupled to said input winding, during conduction of said clamp switch;
a rectifier circuit, coupled to said conversion circuit, that provides rectification of said output energy transfer; and
an output filter, coupled to said rectifier circuit, that provides an output voltage from said rectification of said output energy transfer.
21. The converter as recited in claim 20 wherein a second transformer, having an input winding coupled to secondary winding, that forms an intermediate circuit mesh and extends said output energy transfer, through the output windings coupled to said input winding, during conduction of said power and clamp switches;
22. The converter as recited in claim 20 wherein a reverse current circulating in said intermediate circuit mesh is coupled to said primary winding to extend zero-voltage switching (ZVS) opportunity of said power and clamp switches.
23. The converter as recited in claim 22 wherein said reverse current circulates during an interval between non-conducting and conducting periods of said power and clamp switches.
24. The converter as recited in claim 22 wherein further comprising a leakage inductance in said intermediate circuit mesh to provide said reverse current.
25. The converter as recited in claim 22 wherein further comprising a leakage inductance in series with an auxiliary inductance in said intermediate circuit mesh to provide said reverse current.
26. The converter as recited in claim 22 wherein said primary, secondary and input windings use a same voltage phase, and output winding uses an opposite voltage phase.
27. The converter as recited in claim 21 wherein said primary, secondary and input windings and one output use a same voltage phase, and other output winding uses an opposite voltage phase.
28. The converter as recited in claim 20 wherein a volt-second requirement for said second transformer is less than first transformer.
29. The converter as recited in claim 20 wherein each of said power and clamp switches employs a MOSFET having a parasitic capacitance.