Micropumps with fixed valves

A method for making a micro pump comprising the steps of:

• forming a pump cavity in a silicon base
• forming in the base a first conduit having no moving parts and an inner end connected to the cavity and an outer ends the conduit conducting fluid flow between the inner and outer end along a flow path that departs on a straight line;
• forming in the base a second conduit having no moving parts and an inner end connected to the cavity and an outer end;
• and
• shaping the second conduit so that fluid flow there through is restricted less in the direction toward the cavity than in the direction away from the cavity,
• wherein the step of forming said first conduit further comprises forming a portion of the first conduit to have a curved sidewall for directing fluid flow therethrough.

A micromachined pump apparatus comprising:

• a base comprising silicon and having a cavity formed therein
• a first conduit formed in the base and having, an inner end connected to the cavity and an outer ends and having a flow oath defined by the conduit for conducting fluid between the inner end and the outer end, the first conduit being shared so that the flow path depart from a straight line, thereby to change the direction of flow of fluid therethrough;
• and
• a second conduit formed in the base and having an inner end connected to the theretbrough is restricted less in the direction from the outer end to the inner end than in the direction from the inner end to the outer end wherein the first conduit has at least one curved sidewall located so that whenever fluid flows through the first conduit in the direction from the outer end to the inner end, the flow is directed along the curved sidewall.

A method of manufacturing a pump comprising the steps of:

• etching a cavity into a surface of a base;
• etching an inlet valve into the base and in fluid communication with the cavity, the substantial length of the inlet valve being shaped to diffuse fluid flow in the direction toward the cavity;
• etching an outlet valve into the base and in fluid communication with the cavity, the substantial length of the outlet valve being shaped to diffuse fluid flow in the direction away from the cavity;
• said inlet and outlet valves being sized to provide low Reynolds number non-turbulent flow therein, and
• enclosing the cavity with a deformable member to define a cavity volume, the member being deformable for successively increasing and decreasing the cavity volume.

A micromachined pump system, comprising:

• a base;
• a valve conduit formed by micromachining in the base and having an inner end and an outer end, and having a flow path defined by the conduit for conducting fluid therethrough, the valve conduit being shaped so that fluid flow therethrough is restricted less in the direction from the outer end to the inner end than in the direction from the inner end to the outer end;
• wherein fluid flow in said conduit is characterized by low Reynolds numbers where flow is not turbulent;
• and
• a micromachined pump connected to the valve conduit for pumping fluid therethrough.

A micromachined pump apparatus comprising:

• a base comprising silicon and having a cavity formed therein;
• a first conduit formed in the base and having an inner end connected to the cavity and an outer end, and having a flow path defined by the conduit for conducting fluid therethrough, the first conduit being shaped so that the flow path departs from a straight line by an angle of about 90.degree. thereby to change the direction of flow of fluid therethrough;
• and
• a second conduit formed in the base and having an inner end connected to the cavity and an outer end, and having a flow path defined by the conduit for conducting fluid between the inner end and the outer end, the second conduit being shaped so that fluid flow therethrough is restricted less in the direction from the outer end to the inner end than in the direction from the inner end to the outer end.

A micromachined pump apparatus comprising:

• a base comprising silicon and having a cavity formed therein;
• a first conduit formed in the base and having an inner end connected to the cavity and an outer end, and having a flow path defined by the conduit for conducting fluid been the inner end and the outer end, the first conduit being shaped so that the flow oath departs from a straight line thereby to change the direction of flow of fluid therethrough:
• and
• a second conduit formed in the base and having an inner end connected to the cavity and an outer end, the second conduit being, shaped so that fluid flow therethrough is restricted less in the direction from the outer end to the inner and than in the direction from the inner end to the outer end;
• and
• a deformable cover plate secured to the base covering the cavity and the first and second conduits.

A micromachined pump system, comprising:

• a base;
• a valve conduit formed by micromachining in the base and having an inner end and an outer end, and having a flow path defined by the conduit for conducting fluid therethrough, the valve conduit being shaped so that fluid flow therethrough is restricted less in the direction from the outer end to the inner end than in the direction from the inner end to the outer end;
• and
• a micromachined pump connected to the valve conduit for pumping fluid therethrough, wherein the valve conduit has at least one curved sidewall located so that whenever fluid flows through the valve conduit in the direction from the outer end to the inner end, the flow is directed along the curved sidewall.

A micromachined pump system, comprising:

• a base;
• a valve conduit formed in the base and having an inner end and an outer end, and having a flow path defined by the conduit for conducting fluid therethrough, the valve conduit being shaped so that fluid flow therethrough is restricted less in the direction from the outer end to the inner end than in the direction from the inner end to the outer end;
• and
• a micromachined pump connected to the valve conduit for pumping fluid therethrough wherein the valve conduit is shaped so that the flow path departs from a straight line by an angle of about 90.degree. changing the direction of flow of fluid therethrough.