Miniature fixed and adjustable flow restrictor for the body

Patent metadata

Field	Value
Publication number	US-12004996-B2
Application number	US-202217984046-A
Country	US
Kind code	B2
Filing date	Nov 9, 2022
Priority date	May 22, 2018
Publication date	Jun 11, 2024
Grant date	Jun 11, 2024

Abstract

A microfluidic flow restrictor that uses micron-sized beads to impede flow is described. The flow rate can be adjusted by adding or removing the beads using injection needles through self-sealing ports, one injection needle injecting or aspirating beads and another injection needle pushing or pulling fluid from outside of a bead trap within the flow restrictor. In alternative embodiments, the beads or other filler material can be trapped in a manifold bead trap such that they block a subset of fluid channels of the flow restrictor, allowing fluid to flow freely through the rest of the fluid channels. The flow restrictor can be integrated with a contact lens or implantable medical device for use in dispensing liquid therapeutic agents at flow rates of microliters per minute or moving body fluids at a controlled rate from one part of the body to another.

First claim

What is claimed is:

1. A method of adjusting a microfluidic flow restrictor, the method comprising:
a fluid flow rate through a microfluidic flow restrictor having a bead trap with a fill port;
piercing the fill port with a first injection needle;
piercing a downstream port of the microfluidic flow restrictor with a second injection needle;
injecting chemically inert spherical beads into, or aspirating chemically inert spherical beads out of, the bead trap in the microfluidic flow restrictor using the first injection needle, the chemically inert spherical beads having a diameter between 10 μm and 100 μm, thereby adjusting a fluidic resistance of the microfluidic flow restrictor;
pulling or pushing fluid with the second injection needle contemporaneously with the injecting or aspirating of the first injection needle in order to assist movement of the spherical beads; and
re-measuring the fluid flow rate after the injecting.

2. The method of claim 1 further comprising:
vibrating, using an ultrasound transducer, a wall of the microfluidic flow restrictor in order to dislodge spherical beads.

3. A microfluidic flow restrictor apparatus comprising:
multiple parallel fluid channels, each fluid channel having a bead stop;
a manifold connected with and running perpendicular to the fluid channels;
a first bead stop within the manifold, the first bead stop of the manifold and bead stops of the multiple parallel fluid channels forming a single bead trap within the manifold;
a fill port extending from an outside into an interior of the bead trap; and
a downstream port extending from the outside to a portion of the manifold not within the bead trap.

4. The apparatus of claim 3 further comprising:
a non-pierceable needle stop on or within a wall opposite at least one of the fill port or the downstream port.

5. The apparatus of claim 4 wherein the non-pierceable needle stop comprises glass.

6. The apparatus of claim 3 further comprising:
a plurality of chemically inert spherical beads within the bead trap and against a bead stop of a first fluid channel of the multiple fluid channels and not against a bead stop of a second fluid channel of the multiple fluid channels, thereby blocking the first fluid channel with respect to the second fluid channel.

7. The apparatus of claim 6 wherein the spherical beads each have a diameter between 10 μm and 100 μm.

8. The apparatus of claim 6 further comprising:
a liquid flowing within the first fluid channel, the beads within the bead trap causing a pressure drop of less than 103 kilopascals (15 pounds per square inch).

9. The apparatus of claim 6 wherein the spherical beads are porous.

10. The apparatus of claim 3 wherein at least one of the port fill port and the downstream port is dyed so as to be visually contrasted from other portions of the flow restrictor apparatus.

11. The apparatus of claim 3 wherein at least one of the fill port and the downstream port is thicker than walls of the manifold.

12. The apparatus of claim 11 wherein the fill port and the downstream port each comprise silicone rubber and have a thickness greater than 160 μm so as to make them self-sealing to a 21-gauge injection needle.

13. The apparatus of claim 11 wherein the fill port and the downstream port each comprise parylene C and have a thickness greater than 5 μm so as to make them self-sealing to a 21-gauge injection needle.

14. A contact lens comprising:
the microfluidic flow restrictor apparatus of claim 3 ;
a reservoir connected with an inlet of the flow restrictor apparatus; and
an eye-contacting surface connected with an outlet from the microfluidic flow restrictor apparatus.

15. The apparatus of claim 3 wherein the bead trap has a length of less than 1 centimeter.

16. The apparatus of claim 3 wherein the fluid channel, the first and second bead stops, and the fill port have squared off corners resulting from photolithography and etching.

Assignees

• California Inst Of Techn
• Univ Southern California

Inventors

• Tai Yu-Chong
• Shapero Aubrey M
• Scianmarello Nicholas E
• Humayun Mark S

Classifications

• A61M31/002

  Devices for releasing a drug at a continuous and controlled rate for a prolonged period of time (artificial gland structures or devices A61F2/022; intra-uterine contraceptive devices A61F6/14; tampons for introducing into the vagina A61F13/20, A61L15/00; suppositories or bougies for intra-vaginal or intra-uterine application A61K9/02; physical forms of medicinal preparations for sustained or differential drug release A61K9/20, A61K9/50) · CPC title

• A61F2250/0068

  the pharmaceutical product being in a reservoir · CPC title

• G02C7/049

  Contact lenses having special fitting or structural features achieved by special materials or material structures · CPC title

• B01L2400/082

  Active control of flow resistance, e.g. flow controllers · CPC title

• A61K9/0051

  Ocular inserts or implants · CPC title