Method and/or apparatus for puncturing a surface for extraction, in situ analysis, and/or substance delivery using microneedles
View Patent ↗A method and apparatus for puncturing a surface for extraction, in situ monitoring, and/or substance delivery uses microneedles with improved properties. Applications include easy to handle glucose monitoring using a group of hollow out-of-plane silicon microneedles to sample substances in interstitial fluid from the epidermal skin layer.
1. A microneedle comprising:
a needle shaft with a solid tip, said shaft extending vertically above a needle base;
said needle base defining a first plane (A) parallel to said base and said shaft defining a vertical line (B) substantially perpendicular to said first plane;
an opening on said shaft, said opening being completely surrounded by solid material above said base nearer to said base than to said tip thereby forming a hollow microneedle;
said opening having surrounding walls within said shaft that are substantially parallel to said vertical line; and
a groove that runs along said shaft from said tip providing a recessed channel from said tip to said opening and terminates into said opening of said hollow microneedle, said groove defining a groove line (C), said groove at an acute angle from said vertical line;
such that said tip can puncture a surface in order to deliver or sample fluids with reduced blockage of said opening, said opening being substantially distant from said solid tip, said groove providing fluidic guidance from said solid tip to said opening.
2. The device of claim 1 further comprising:
said needle shaft is between about 100 to 5000 micrometers in height.
3. The device of claim 1 further comprising:
said needle shaft is between about 100 to 450 micrometers in height.
4. The device of claim 1 further wherein:
said opening comprises an off-center through-hole that is completely surrounded by solid material a substantial distance below said tip; and
said groove extends from said tip to the top of the off-center through-hole wherein said groove allows for a greater total shaft height.
5. The device of claim 1 further comprising:
said opening is surrounded on all sides beginning at least 60% below said tip on said needle shaft height and above said base; and
said groove extends substantially from said needle tip to said opening.
6. The device of claim 1 further comprising:
said opening is surrounded on all sides beginning at least 90% below said tip on said needle shaft height and above said base; and
said groove extends from said needle tip to said opening.
7. The device of claim 4 further wherein:
said through hole becomes completely surrounded by solid material on said needle shaft in a plane roughly perpendicular to the needle shaft no more than 50% above said base.
8. The device of claim 1 further comprising:
said solid tip and said groove comprise at least 60% of said needle shaft height.
9. The device of claim 1 further comprising:
said solid tip and said groove comprise at least 80% of said needle shaft height.
10. The device of claim 1 further wherein:
said groove guides fluid flow between said tip and said through hole.
11. The device of claim 1 further comprising:
a substrate in contact with said base, said substrate providing support for said base, said hole extending into to said substrate to connect with one or more microchannels in said substrate.
12. The device of claim 1 further comprising:
a compensation structure between an underside hole of said needle and a channel floor, said structure easing fluid flow.
13. The device of claim 1 further wherein:
said opening is formed by etching.
14. The device of claim 1 further wherein:
said opening is formed by laser ablation.
15. The device of claim 1 further wherein:
said opening is formed using a mold.
16. The device of claim 1 further wherein:
said opening is formed using a drill.
17. The device of claim 4 further wherein a recessed portion of said groove is protected from blockage by cellular bodies.
18. The device of claim 4 further wherein said groove comprises a rough surface providing increased surface area that increase capillary fluid flow.
19. The device of claim 4 further wherein said groove comprises a recessed channel providing a location for fluid transfer that is somewhat protected from blockage of cellular bodies.
20. The device of claim 4 further wherein said off-center through-hole provides improved capillary flow.
21. The device of claim 4 further wherein:
said opening comprises an off-center through-hole that fully opens a substantial distance below the tip; and
said groove extends from said tip to the top of the off-center through-hole wherein said groove allows for a greater diameter bore-hole.