Micromachined membrane filter device for a glaucoma implant and method for making the same

A MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• a membrane having a plurality of pores, sized to achieve a therapeutic flow rate while substantially preventing bacterial passage therethrough;
• a pair of substrates disposed on opposing sides of the membrane, each having a cross-shaped support supporting the membrane and an axial inlet opening at a distal end thereof;
• and
• a conformal coating covering the membrane and the substrates.

A method of manufacturing a MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• etching a recess on a first end of a substrate to support a membrane;
• conformally depositing a core membrane on the first end of the substrate, covering the recess;
• etching an initial size of pores in the membrane;
• etching a central portion of the substrate from a second end, opposite the first end, until the membrane is reached;
• and
• conformally coating the membrane and substrate, whereby a size of the pores is finalized and the membrane is strengthened.

A MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• a first substrate having a passage therethrough;
• a membrane having a plurality of pores, substantially uniformly sized to achieve a therapeutic flow rate while substantially preventing bacterial passage therethrough, the membrane being disposed at a first end of the first substrate;
• and
• a second substrate having a recess to accommodate the membrane, the second substrate having a plurality of axial passages acting as a pre-filter to the membrane, the second substrate being bonded at an outer peripheral portion thereof to an outer peripheral portion of the first substrate such that the axial passages of the second substrate substantially align with the passage of the first substrate.

A method of manufacturing a MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• depositing a membrane layer on a first substrate;
• removing a portion of the membrane layer by patterning to define a bonding area on the first substrate;
• patterning pores in the membrane layer to define an initial size of the pores;
• backside etching the substrate to the membrane layer;
• conformally coating the membrane layer and the first substrate to finalize the pore size;
• etching a cavity in a second substrate to accommodate the membrane;
• etching inlet ports in the second substrate to function as a pre-filter for the membrane;
• and
• fusion boding the second substrate on the bonding area of the first substrate.

A MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• a membrane having a plurality of pores, substantially uniformly sized to achieve a therapeutic flow rate while substantially preventing bacterial passage therethrough;
• a pair of substrates, each bonded to an opposing side of the membrane, and each having an axial inlet opening at a distal end thereof;
• and
• a cross-shaped support disposed in one of the substrates, the cross-shaped support supporting the membrane.

A method of manufacturing a MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• depositing a membrane layer on a substrate;
• patterning pores in the membrane layer to define an initial size of the pores;
• backside etching the substrate to the membrane layer;
• and
• conformally coating the membrane layer.

A method of manufacturing a MEMS-fabricated filter device for an ophthalmic shunt, comprising:

• defining pores in a silicon membrane layer of a silicon on insulator (SOI) wafer using a first photo mask;
• oxidizing a top and bottom of a silicon wafer to define a mask side and an etch stop side of the silicon wafer;
• creating alignment marks on the silicon wafer using a second photo mask;
• fusion bonding the etch stop side of the silicon wafer to the silicon membrane of the SOI wafer;
• annealing the wafers and oxidizing exposed ends of the wafers;
• etching the oxide on the silicon wafer and deep reactive ion etching the silicon of the silicon wafer to the etch stop oxide of the silicon wafer using the second photo mask;
• etching the oxide on the SOI wafer and deep reactive ion etching the silicon of the SOI wafer to the insulator of the SOI wafer using a third photo mask;
• removing the oxide on opposing sides of the silicon membrane layer using a timing etch;
• and
• cover coating the silicon membrane layer, SOI wafer, and the silicon wafer.