Injection molded, heat-sealed housing and half-etched lead frame for oximeter sensor

• US 5,913,819 A
• Filed: 04/07/1997
• Issued: 06/22/1999
• Est. Priority Date: 04/26/1996
• Status: Expired due to Fees

• Current Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Original Assignee: Datex-Ohmeda Incorporated (General Electric Company)
• Inventors: Taylor, James H., Weimer, Kirk L., Estoque, Daniel A.
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US08/826,698
• Time in Patent Office: 806 Days
• Field of Search: 600/310, 600/322, 600/323, 600/340, 600/344, 29/832, 29/846, 29/847, 29/848
• US Class Current: 600/323
• CPC Class Codes: A61B 46/10 specially adapted for instruments, e.g. microscopes
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.
• CPC Class Codes: Y10T 29/49156 with selective destruction of conductive paths

Abstract

The present invention is directed to an oximeter sensor to measure the oxygen content of a patient'"'"'s blood. The sensor can include a lead frame having different thicknesses, a sensor housing being molded from a common thermoplastic resin, and rib members in the housing for inhibiting shorting between adjacent traces of the lead frame. The present invention further includes a process for forming the sensor.

Claims

1. In a sensing device for measuring the oxygen content of a patient'"'"'s bloodstream, the sensing device comprising:

a leadframe for operatively connecting at least one of (a) an emitter means for irradiating the patient'"'"'s bloodstream and (b) a detector means for providing a signal in response to a radiation portion passing through the bloodstream to an oximeter processing and display unit, the leadframe having a first portion having a first thickness and a second portion having a second thickness with the first thickness being greater than the second thickness.

2. The sensing device of claim 1, wherein the first portion of the leadframe contacts at least one of the detector means and the emitter means.

3. The sensing device of claim 1, wherein the first thickness ranges from about 10 to about 20 mils.

4. The sensing device of claim 1, wherein the detector means and emitter means are at opposite ends of the leadframe and the second portion of the leadframe is located between the detector means and emitter means.

5. The sensing device of claim 1, wherein the second thickness ranges from about 5 to about 10 mils.

6. The sensing device of claim 1, wherein the leadframe comprises a first set of traces between the emitter means and detector means and a second set of traces extending from the emitter means to wire means for connecting the sensing device to an oximeter processing and display unit, the first portion including the second set of traces and the second portion including the first set of traces.

7. The sensing device of claim 1, further comprising a housing for containing the at least one of the emitter means and detector means, the housing including a substantially transparent lens adjacent to the at least one of the emitter means and detector means and a housing body enclosing the at least one of the emitter means and detector means, wherein the housing body and lens are composed of the same base thermoplastic material and have substantially the same degree of elasticity;

wherein the lead frame includes a plurality of spaced-apart traces and the housing body includes a plurality of rib members, with one or more rib members being received between adjacent traces; and

wherein the housing has upper and lower portions and the upper and lower portion each has a lip portion projecting outwardly from the corresponding one of the upper and lower portions, the lip portion of the upper portion being sealed to a lip portion on the lower portion to protect at least one of the emitter means and detector means from fluids in the terrestrial environment.

8. In a sensing device for measuring the oxygen content of a patient'"'"'s bloodstream, the sensing device comprising:

a housing for containing at least one of (a) an emitter means to irradiating the patient'"'"'s bloodstream and (b) a detector means for providing a signal in response to a radiation portion passing through the bloodstream, the housing including a substantially transparent lens adjacent to the at least one of the emitter means and detector means and a housing body enclosing the at least one of the emitter means and detector means, wherein the housing body and the lens are composed of the same base thermoplastic material that at least one of the melting point, yield tensile strength, ultimate tensile strength, modulus of elasticity, coefficient of thermal expansion, and durometer of the lens is within about 10% of a corresponding at least one of the melting point, yield tensile strength, ultimate tensile strength, modulus of elasticity, coefficient of thermal expansion, and durometer of the housing body, and wherein the lens is molded to the housing to provide a sealed and smooth transition therebetween.

9. The sensing device of claim 8, wherein the lens is substantially free of color bodies.

10. The sensing device of claim 8, wherein the housing body contains color bodies.

11. The sensing device of claim 8, wherein the housing body contains from about 2 to about 30% by weight color bodies.

12. The sensing device of claim 8, wherein thermoplastic resin forming the lens has substantially the same melting point as the thermoplastic resin forming the housing body.

13. The sensing device of claim 8, wherein the difference between the melting point of the thermoplastic resin forming the lens and melting point as the thermoplastic resin forming the housing body is no more than about 25°

F.

14. The sensing device of claim 8, wherein the melting point of the thermoplastic resin forming the lens is at least about 75% and no more than about 125% of the melting point of the thermoplastic resin forming the housing body.

15. The sensing device of claim 8, wherein the housing body and lens have substantially the same degree of elasticity and has upper and lower portions with the upper and lower portion each having a lip portion projecting outwardly from the corresponding one of the upper and lower portions, the lip portion of the upper portion being sealed to a lip portion on the lower portion to protect at least one of the emitter means and detector means from fluids in the terrestrial environment, and further comprising a lead frame for operably connecting at least one of the emitter means and detector means to an oximeter processing and display unit, the lead frame having a first portion having a first thickness and a second portion having a second thickness with the first thickness being greater than the second thickness and wherein the lead frame includes a plurality of spaced-apart traces and the housing body includes a plurality of rib members, with one or more rib members being received between adjacent traces.

16. In a sensing device for measuring the oxygen content of a patient'"'"'s bloodstream, the sensing device comprising:

a housing for containing at least one of (a) an emitter mean for irradiating the patient'"'"'s bloodstream and (b) a detector means for providing a signal in response to a radiation portion passing through the bloodstream, the housing including a substantially transparent lens adjacent to the at least one of the emitter means and detector means and a housing body enclosing the at least one of the emitter means and detector means, and wherein the lens is molded to the housing to provide a sealed and smooth transition therebetween.

17. The sensing device of claim 16, wherein the lens is substantially free of color bodies.

18. The sensing device of claim 16, wherein lens and housing body are composed of the same base thermoplastic material.

19. The sensing device of claim 16, wherein the housing body contains from about 2 to about 30% by weight color bodies.

20. The sensing device of claim 16, wherein thermoplastic resin forming the lens has substantially the same melting point as the thermoplastic resin forming the housing body.

21. The sensing device of claim 16, wherein the difference between the melting point of the thermoplastic resin forming the lens and melting point as the thermoplastic resin forming the housing body is no more than about 25% .

22. The sensing device of claim 16, wherein the melting point of the thermoplastic resin forming the lens is at least about 75% and no more than about 125% of the melting point of the thermoplastic resin forming the housing body.

23. The sensing device of claim 16, wherein the housing body and lens are composed of the same base thermoplastic material and has upper and lower portions with the upper and lower portion each having a lip portion projecting outwardly from the corresponding one of the upper and lower portions, the lip portion of the upper portion being sealed to a lip portion on the lower portion to protect at least one of the emitter means and detector means from fluids in the terrestrial environment, and further comprising a lead frame for operatively connecting at least one of the emitter means and detector means to an oximeter processing and display unit, the lead frame having a first portion having a first thickness and a second portion having a second thickness with the first thickness being greater than the second thickness and wherein the lead frame includes a plurality of spaced-apart traces and the housing body includes a plurality of rib members, with one or more rib members being received between adjacent traces.

24. In a sensing device for measuring the oxygen content of a patient'"'"'s bloodstream, the sensing device comprising:

a housing enclosing (a) at least one of an emitter means for irradiating the patient'"'"'s bloodstream and a detector means for providing a signal in response to a radiation portion passing through the bloodstream and (b) a leadframe for operatively connecting the at least one of the emitter means and detector means with an oximeter processing and display unit, wherein the leadframe includes a plurality of bare, spaced-apart, conductive traces and the housing body includes a plurality of rib members, with one or more rib members being positioned between adjacent traces to align and electrically isolate the bare traces.

25. The sensing device of claim 24, wherein the thickness of the rib members is at least 25% of the distance between adjacent traces.

26. The sensing device of claim 24, wherein a first set of traces is located between the detector means and the emitter means and a second set of traces is located between the at least one of the detector means and emitter means and wire means for connecting the sensing device to the oximeter processing and display unit and a first set of rib members engages the first set of traces and a second set of rib members engages the second set of traces.

27. The sensing device of claim 24, wherein a first portion of a first rib member received between adjacent traces has a greater width than an adjacent portion of the first rib member, thereby defining a nub.

28. The sensing device of claim 27, wherein a second rib member is adjacent to the first rib member, the second rib member comprising a second portion having a width greater than an adjacent portion thereof and wherein the distance between the first portion of the first rib member and the second portion of the second rib member is less than the width of a trace received therebetween.

29. The sensing device of claim 24, wherein the lead frame has a first portion having a first thickness and a second portion having a second thickness with the first thickness being greater than the second thickness and the housing includes a housing body and lens, with the housing body and lens being composed of the same base thermoplastic material and having the same degree of elasticity and has upper and lower portions with the upper and lower portion each having a lip portion projecting outwardly from the corresponding one of the upper and lower portions, the lip portion of the upper portion being sealed to a lip portion on the lower portion to protect at least one of the emitter means and detector means from fluids in the terrestrial environment.

30. In a sensing device for measuring the oxygen content of a patient'"'"'s bloodstream, the sensing device comprising:

a housing enclosing at least one of an emitter means for irradiating the patient'"'"'s bloodstream and a detector means for providing a signal in response to a radiation portion passing through the bloodstream, wherein the housing has adjoined upper and lower portions, and wherein the upper portion and lower portion are heat-sealed together about their respective peripherals to form a lip portion projecting outwardly from the upper and lower portions, the lip portion protecting emitter means and detector means from fluids in the terrestrial environment.

31. The sensing device of claim 30, wherein at least one of the lip portions has a tongue or a groove to engage a groove or a tongue, respectively, on the other lip portion.

32. The sensing device of claim 30, wherein the upper and lower portions of the housing form a housing body and include a lens adjacent to at least one of the emitter means and detector means and wherein the housing body and lens are composed of the same base thermoplastic material and have the same degree of elasticity and further comprising a lead frame for operatively connecting at least one of the emitter means and detector means to an oximeter processing and display unit, the lead frame having a first portion having a first thickness and a second portion having a second thickness with the first being greater than the second thickness and the lead frame including a plurality of spaced-apart traces and the housing body including a plurality of rib members, with one or more rib members being received between adjacent traces.

33. A method for forming a leadframe for an oximeter sensing device, comprising:

cutting a leadframe body from a conductive sheet; and

applying an etchant to a selected portion of the leadframe body to form a leadframe having different thicknesses.

34. The method of claim 33, wherein the applying step comprises:

applying a masking material to a second portion of the leadframe body other than the selected portion; and

applying the etchant to the selected portion and the second portion.

35. The method of claim 33, wherein the applying step comprises:

applying the etchant only to the selected portion of the leadframe body.

36. The method of claim 33, wherein the applying step comprises:

etching the selected portion of the leadframe body for a first time period; and

etching another portion of the leadframe for a second time period, wherein the first time period exceeds the second time period.

37. The method of claim 33, wherein the cutting step comprises cutting the leadframe from a conductive sheet using a cutting die having substantially the same size and shape as a cavity in an oximeter sensor housing for receiving a leadframe and further comprising:

forming a thermoplastic resin;

molding a first portion of the thermoplastic resin to form a light transparent lens for at least one of a detector and emitter;

mixing a second portion of the thermoplastic resin with a color body to form a substantially light opaque, thermoplastic resin;

molding the substantially light opaque, thermoplastic resin to form a housing body having upper and lower portions for enclosing a lead frame, the upper portion of the housing having a first lip projecting outwardly from the upper portion for engaging a second lip on the lower portion with the second lip projecting outwardly from the lower portion;

engaging the first lip with the second lip; and

heating the upper and lower portions to above the melting point of the first and second lips to seal the upper portion and the lower portion.

38. A method for manufacturing an oximeter sensor, comprising:

cutting a conductive sheet to define a leadframe having a plurality of conductive traces using a cutting die having substantially the same size and shape as a cavity in an oximeter sensor housing for receiving the leadframe;

positioning the leadframe and plural traces into said cavity of the oximeter sensor housing.

39. The method of claim 38, wherein the distance between the edge of the cavity and the outer edge of the leadframe is no more than about 25 mils.

40. The method of claim 38, further comprising:

applying an etchant to a selected portion of the lead frame body to form a lead frame having different thicknesses;

forming a thermoplastic resin;

molding a first portion of the thermoplastic resin to form a light transparent lens for at least one of a detector and emitter;

mixing a second portion of the thermoplastic resin with a color body to form a substantially light opaque thermoplastic resin;

forming upper and lower portions of the housing for enclosing the lead frame, the upper portion of the housing having a first lip projecting outwardly from the upper portion for engaging a second lip on the lower portion with the second lip projecting outwardly from the lower portion;

engaging the first lip with the second lip; and

heating only the first lip and second lip to above the melting point of the first and second lips to seal the upper portion to the lower portion.

41. A method for forming an oximeter sensing device, comprising:

forming a thermoplastic resin;

molding a first portion of the thermoplastic resin to form a light transparent lens for at least one of a detector and emitter;

mixing a second portion of the thermoplastic resin with a color body to form a substantially light opaque thermoplastic resin, said second portion being separate from the first portion; and

molding the substantially light opaque thermoplastic resin to form a housing body for the oximeter sensing device;

including;

positioning the light transparent lens for at least one of a detector and emitter in a mold for the housing body; and

contacting the mold with the substantially light opaque thermoplastic resin, the substantially light opaque thermoplastic resin having a temperature at or above the melting temperature of the thermoplastic resin; and

cooling the substantially light opaque thermoplastic resin to form the housing body, wherein the lens is molded to said housing body.

42. The method of claim 41, wherein the molding step comprises:

forming upper and lower portions of the housing for enclosing the lead frame, the upper portion of the housing having a first lip projecting outwardly from the upper portion for engaging a second lip on the lower portion with the second lip projecting outwardly from the lower portion;

engaging the first lip with the second lip; and

heating the upper and lower portions to above the melting point of the first and second lips to seal the upper portion to the lower portion; and

further comprising;

cutting the lead frame from a conductive sheet using a cutting die having substantially the same size and shape as a cavity in the housing for receiving the lead frame; and

applying an etchant to a selected portion of the lead frame body to form a lead frame having different thicknesses.

43. A method for forming an oximeter sensing device, comprising:

forming upper and lower portions of a housing for enclosing a leadframe, the upper portion of the housing having a first lip projecting outwardly from the upper portion for engaging a second lip on the lower portion with the second lip projecting outwardly from the lower portion;

engaging the first lip with the second lip; and

heating the first lip and second lip to above the melting point of the first and second lips to heat-seal the upper portion to the lower portion wherein said heating is restricted to said first lip and said second lip.

44. The method of claim 43 wherein the forming step comprises:

forming a thermoplastic resin;

molding a first portion of the thermoplastic resin to form a light transparent lens for at least one of a detector and emitter;

mixing a second portion of the thermoplastic resin with a color body to form a substantially light opaque thermoplastic resin; and

molding the substantially light opaque thermoplastic resin to form a housing body for the oximeter sensing device; and

further comprising;

cutting the lead frame from a conductive sheet using a cutting die having substantially the same size and shape as a cavity in an oximeter sensor housing for receiving the lead frame; and

applying an etchant to a selected portion of the lead frame body to form a lead frame having different thicknesses.