Surgical Scalpel

Micromachined surgical scalpel

A multilevel structures is formed with the cubic crystal material typically silicon. Structures with {111} sidewalls are formed for a desired etching depth on the surface of a (100) silicon wafer by a conventional masked anisotropic etching process using a specially designed etching mask. Then, the etching mask is removed except for some areas (including the frame area) and a maskless etching follows. In the downward etching of the upper and lower (100) planes during maskless etching, the {111] sidewalls will finally be replaced by {311} planes. The cutting edge apex angle is 25.24 degrees and is that angle determined by the intersection of the {100} and {311] planes. The multilevel structures can be used as scalpels in surgery.

1. A micromachined cutting blade, comprising a body of single cubic crystal having at least one linear cutting edge defined by the intersection of two crystal planes having an apex angle of intersection and with crystal plane surfaces obtained by micromachining using the dissolved silicon etch process of anisotropic etching and with the crystal plane surfaces obtained using surface photomask films selectively removed at steps during said dissolved silicon processing.

2. The blade of claim 1 with the cutting edge formed by the intersection of {311} and {100} planes to form an apex angle of 25 degrees.

3. The blade of claim 1 with the cutting edge formed by the intersection of {311} and {311} planes to form an apex angle of 50 degrees.

4. The blade of claim 1 with a plurality of cutting edges formed as a continuous cutting line.

5. The blade of claim 4 with multiple cutting edges forming a serrated cutting line.

6. The blade of claim 1 formed of silicon single cryctal.

7. The blade of claim 1 with structures formed into or on the blade for the purpose of heating, temperature sensing, and/or detecting broken cutting edges.

Medical Supplies Patent

KOH etches the {111} sidewalls slowly and the {100} horizontal surface faster and thereby creates the cross section of FIG. 3.

[0026] The depth of the {1 00} cavity is 110 micrometers in this embodiment. The separation of the ribs is 110 and 219 micrometers. The initial width of the cavity on photomask 101 is 845 micrometers.

[0027] The cross section of FIG. 4 is next achieved by selectively etching the silicon nitride 403 from the silicon surface to expose additional silicon surface for further etching. The next KOH etching procedure is performed on the structure seen in FIG. 5 to obtain the deeper etched structure of FIG. 5. The {311} plane appears as a fast etching plane at the edge of the {111} sidewalls. As the {311} planes replaces the {111} sidewalls with a rate faster than the extension rate of the {111} planes, the {111} sidewall is replaced by the {311} planes. Levels with different depths 505, 508, 509, can be created in this way for different window apertures and the depths of the new levels can be individually determined by the design of the mask for masked etching. The end point of etching in FIG. 5 is determined by stopping the etch at or near the time at which the sharp knife edge is formed.

[0028] A larger view of the structure of FIG. 5 is shown in the isometric view of FIG. 6. This figure shows the full wafer thickness around the 3 peripheral boundaries of the micromachined structure. The fourth peripheral plane is parallel to the {100} plane is obtained by sawing the wafer into die (individual scalpels).

[0029] A variation in the embodiment 1 masking process can be used to obtain embodiment 2 of FIG. 6. In embodiment 2 a single side of the silicon wafer 602 is micromachined to create the top surface identical to embodiment 1. The backside is masked in a very conventional way to define the deep etch into the {100) planes to produce a knife with a thinner blade in the cutting area. The backside mask is a single photomask #3 which is not patterned until the backside is to be etched. The backside etch can be done simultaneous with the deep frontside etch or it can be done separately.

[0030] A third embodiment 3 can be obtained by applying the same masking with photomasks #1 and #2 to both the front and back sides of the wafer and with these two masks aligned with respect to one another. The result is the structure of 601 on FIG. 6 with a 50.48 degree apex angle for the cutting edge. This apex angle of FIG. 6 is formed by the intersection of the {311} and {311} planes.

[0031] Other cubic structure crystals that have etch planes similar to silicon include gallium arsenide can also be etched anisotropically using well known etchants.

[0032] The intersection of the {311} and {111} planes can be used to define multiple cutting edges. For instance, a 3-edged cutting tool can be obtained by defining the three orthogonal intersection edges using anisotropic etching with the fourth side constituting a structural handle.

[0033] Additional patterned structures may be created into the surfaces of the cutting tool. The structures for heating, monitoring surface breakage, and temperature sensing as described by Carr and Ladocsi in U.S. Pat. No. 5,980,518 can be made part of the present cutting tool. These structures are typically created on an original (unetched) {100} crystal surface.

[0034] This technology can be used to create a fourth embodiment which contains a serrated cutting edge by orienting masks at a 90 degree angle within the plane of the starting {111}. A top view of the serrated cutting edge is shown in FIG. 9 as obtained by precisely defining an etch mask which is oriented 90 degrees off the alignment illustrated in FIG. 1.

[0035] It is to be understood that the above-described embodiments are merely illustrative of the invention and that many variations may be devised by those skilled in the art without departing from the scope of the invention and from the principles disclosed herein. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.

  1. Guarded surgical scalpel with blade stripper lock to prevent accidental or inadvertent ejection of the blade
  2. Multi-bladed surgical scalpel
  3. Disposable surgical scalpel
  4. Surgical scalpel and system particularly for use in a transverse carpal ligament surgical procedure
  5. Disposable guarded surgical scalpel
  6. Lock-type disposal safe surgical scalpel
  7. Surgical scalpel with protective sheath
  8. Spring-actuated, retractable-bladed surgical scalpel
  9. Surgical scalpel
  10. Surgical scalpel incinerating device
  11. Surgical scalpel
  12. Multi-bladed surgical scalpel
  13. Shielded surgical scalpel
  14. Micromachined surgical scalpel
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