Flex circuit shielded optical sensor

• US 20020165440A1
• Filed: 05/02/2002
• Published: 11/07/2002
• Est. Priority Date: 05/03/2001
• Status: Active Grant

• Current Assignee: Masimo Corporation
• Original Assignee: Masimo Corporation
• Inventors: Gerhardt, Thomas J., Al-Ali, Ammar, Mason, Gene
• Granted Patent: US 6,985,764 B2
• Time in Patent Office: Days
• US Class Current: 600/344
• CPC Class Codes: A61B 2562/12 Manufacturing methods specially adapted for producing sensors for in-vivo measurements
• CPC Class Codes: A61B 2562/182 Electrical shielding, e.g. using a Faraday cage
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: H05K 1/0218 by printed shielding conductors, ground planes or power plane H05K1/0236 takes precedence
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A flex circuit optical sensor has an integrated Faraday shield. A conductive trace layer disposed on a substrate is used to form a conductive grid which shields the face of a photodetector. A conductive ink layer is formed on a substrate side opposite the trace layer. The back and sides of the detector are shielded by flex circuit flaps that have the conductive ink layer but substantially exclude the trace layer so as to fold over and closely adhere to the detector body. The shielded substrate flaps advantageously eliminate a separate detector shield, which is typically fabricated with an etched copper part that must be attached to a flex circuit before mounting the detector.

Claims

1. An optical sensor comprising:

a flex circuit;

an emitter configured to transmit optical radiation;

a detector configured to receive optical radiation from said emitter,

said detector and said emitter mounted to said flex circuit; and

a plurality of flap portions of said flex circuit each having an unfolded position extending from said flex circuit and a folded position at least partially enclosing said detector.

2. The optical sensor according to claim 1 wherein said flap portions comprise:

a back flap configured to fold over and adhere to a first portion of said detector; and

a side flap configured to fold over and adhere to a second portion of said detector.

3. The optical sensor according to claim 1 wherein said flex circuit comprises:

a substrate layer having a first side and a second side; and

a conductive layer disposed on said second side substantially including said flap portions so that said flap portions in said folded position shield electromagnetic interference from said detector.

4. The optical sensor according to claim 3 further comprising:

a trace layer disposed on said first side providing signal connections for said detector and said emitter; and

a conductive grid portion of said trace layer proximate said flap portions, said grid portion configured to form a Faraday shield for said detector in conjunction with said flap portions.

5. The optical sensor according to claim 4 wherein said trace layer is substantially excluded from said flap portions.

6. An optical sensor comprising:

a flex circuit substrate having a first side and an opposite second side;

a trace layer disposed on said first side having a pattern of conductors so as to electrically connect with an emitter and a detector; and

a conductive grid portion of said trace layer having at least one aperture so as to pass optical radiation from said emitter to said detector, said trace layer configured to mount said detector proximate said grid portion.

7. The optical sensor according to claim 6 wherein said at least one aperture comprises at least one hole drilled through said substrate and said grid.

8. The optical sensor according to claim 6 wherein said substrate is adapted to transmit light and said at least one aperture comprises a pattern etched in said grid.

9. The optical sensor according to claim 6 further comprising a shield layer disposed on said second side, said substrate having a foldable portion including said shield layer and substantially excluding said trace layer, said foldable portion configured to substantially enclose said detector so as to form a Faraday shield in conjunction with said conductive grid portion.

10. The optical sensor according to claim 9 wherein said foldable portion has a plurality of flaps adapted to adhere to said detector.

11. The optical sensor according to claim 6 further comprising:

a stock material retaining said substrate and having a first wrap with a first end and a second wrap with a second end,

each of said wraps adapted for finger attachment of said substrate,

said wraps configured so that, in a wrapped position, said first end covers said second end and said second end terminates distal a person'"'"'s palm.

13. The optical sensor assembly method according to claim 12 wherein said fabricating step comprises the substep of forming a back flap and a plurality of side flaps on said foldable portion.

14. The optical sensor assembly method according to claim 12 wherein said disposing step comprises the substeps of adhering said side flaps to first portions of said detector and adhering said back flap to second portions of said detector.

15. The optical sensor assembly method according to claim 12 further comprising the step of creating a conductive grid portion of at least one of said traces.

16. The optical sensor assembly method according to claim 15 wherein said mounting step comprises the substep of positioning said detector proximate said grid portion so as to shield said detector from electromagnetic interference.

18. The optical sensor according to claim 17 further comprising a grid means portion of said trace means for forming a Faraday shield around said detector.

19. The optical sensor according to claim 18 wherein said grid means comprises an aperture means for transmitting light to said detector.

20. The optical sensor according to claim 17 further comprising a wrap means for finger attachment without an exposed wrap end on the palm of a hand.

12. An optical sensor assembly method comprising the steps of:

fabricating an elongated flex circuit having a component side, an opposite side and a foldable portion;

creating a plurality of traces on said component side substantially excluding said foldable portion;

creating a conductive layer on said opposite side substantially including said foldable portion;

mounting a detector and an emitter to said component side, said traces providing electrical connections for said detector and said emitter; and

disposing said foldable portion around said detector so as to shield said detector from electromagnetic interference.

17. An optical sensor comprising:

a substrate means for supporting a flex circuit;

a trace means disposed on a first side of said substrate means for connecting to a detector and an emitter;

a conductive ink means disposed on a second side of said substrate for shielding said flex circuit; and

a shield means including said substrate means and said conductive ink means for folding onto and attaching to said detector.