WO2008059336A2

WO2008059336A2 - Method and apparatus for testing biological samples using a reader with a conductive housing

Info

Publication number: WO2008059336A2
Application number: PCT/IB2007/003417
Authority: WO
Inventors: David Taylor
Original assignee: Inverness Medical Switzerland Gmbh
Priority date: 2006-11-13
Filing date: 2007-11-08
Publication date: 2008-05-22
Also published as: WO2008059336A3

Abstract

Method and device for the analysis of biological samples are disclosed, wherein the device comprises a reader with an electrically conductive housing, which is electrically coupled to the circuitry inside the housing. This shall avoid damage to the circuitry by reducing the possibility of an electrostatic potential between the housing touched by a user and the circuitry.

Description

TESTING DEVICE AND METHOD

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional U.S. Application No. 60/865,539, filed November 13, 2006, which is incorporated by reference in its entirety.

TECHNICAL FIELD

This invention relates to an assay device and method.

BACKGROUND

A system for measuring a biological sample can use a replaceable cartridge or test strip and a reader. The cartridge accepts a sample and includes one or more reagents for producing a detectable change in the test sample. The detectable change can be related to the amount of an analyte in the sample. The cartridge reader can measure the detectable change and communicate a result to the user. The cartridge reader can calculate the amount of analyte in the sample (e.g. as a concentration of analyte in a liquid sample).¹

The system can be used by users who need to frequently measure an analyte. For example, the system can be useful for patients with a chronic condition that requires monitoring. A static charge can build up on the user which can damage the circuitry of the reader.

SUMMARY

An assay system can include a replaceable assay device and an assay device reader. The assay device can take the form of a cartridge or test strip. The system can provide high sensitivity, low volume detection of an analyte in a sample by optical or electrochemical methods. The system can be simple for patients to use in the home.

In one aspect, a device includes a housing having an outer surface, an opening within the housing to receive a test member and circuitry within the housing. The circuitry can include an interface configured to electrically connect at least a portion of the circuitry with a test member received within the housing, a detector configured to determine a signal indicative of the presence of a substance of interest within a sample in

l a test member received within the housing, a processor in communication with the detector and configured to determine the presence of the substance based at least in part on the signal, and a floating power supply to provide power to the circuitry. The outer surface of the housing can have conductive properties and is conductively coupled to the circuitry such that a likelihood of an electrostatic potential difference between the housing and the circuitry damaging the circuitry is reduced.

In another aspect, a method includes manually manipulating a conductive outer surface of a housing of an assay device, inserting a test member into an opening of the device, introducing a biological sample to the test member, and operating circuitry of the device to determine the presence of an analyte within the biological sample and display a result indicative of the presence of the analyte, the circuitry being powered by a floating power supply internal to the housing. At least one of the steps of manually manipulating and inserting can include reducing or preventing an electrical potential difference between the surface of the housing and the circuitry. In another aspect, a method of measuring a substance in a sample includes a user making contact with a device, for example holding the device, such that the device and circuitry within the device become equipotential with the user, inserting a test member into the device, applying a sample to the test member, and presenting a measurement response to a user. The device can include a housing having an outer surface, a circuitry within the housing including, at least, a detector, a processor, an interface for a test member, a floating power supply to provide power to the circuit, and an opening within the housing to receive a test member, in which the housing has conductive properties and is conductively coupled to the circuit such that build up of an electrostatic potential difference between the housing and the circuit is does not occur. In another aspect, the device for measuring an analyte in a sample obtained from a patient can include a housing having an outer surface, and a circuit contained within the housing. The outer surface can be conductive and can ground the circuit.

In another aspect, a system for measuring an analyte in a sample includes a device including a housing having an outer surface, and a circuit contained within the housing, in which the outer surface can be conductive and can be conductively coupled to the circuit. In another aspect, a method of measuring an analyte in a sample includes touching the device in a manner sufficient to dissipate surface charges on the device or the user, and applying the sample to a device. The device can include a housing having an outer surface, and a circuit contained within the housing. The outer surface can be conductive and conductively couples to the circuit.

The housing or outer surface can include a conductive plastic, conductive polymer, or metal. The housing can include a first portion and a second portion. Each of the first and second portions of the housing can be conductively coupled to the circuitry by a resistor. For example, a housing can include a conductive plastic top, a conductive plastic bottom, or both. The housing can be electrically coupled to the casing by a resistor. The detector can be an electrochemical detector. The detector can be in electrical communication with the test member via the interface. The processor can be configured to receive a signal from the detector and produce a response. The floating power supply is a battery or an isolation transformer. The circuitry can be configured not to receive electrical current from an electrical current source external to the housing. The device can be configured to not operably receive energy from an energy source external to the housing. The power supply can be inductively coupled to an external power supply.

Other features, objects, and advantages will be apparent from the description, the drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an illustration of a device reader. FIG. 2 is an illustration of a cross-section of a device reader. FIG. 3 is an illustration of a circuit of a device reader. FIG. 4 is a schematic top view of a device base. FIG. 5 is a schematic end view of an assembled device.

DETAILED DESCRIPTION

Traditional insulating plastic cases used to produce housings for electronic devices, for example electrochemical test meters, can result in undesirable charge developing on the encased circuit board. The circuit board within the case can acquire a charge relative to external objects. Thus, it is possible that damage can occur to the circuit board due to electrostatic discharge from a user of the device to the internal circuit board because they are at different potentials. A case can be composed of a conductive material, for example, a plastic which incorporates a conductive material. Such a plastic can be used to manufacture a case that can be used to house a circuit board. The circuit board can be fixed into the case in such a way that the ground plane or power rail of the circuit board is conductively coupled to the casing, for example, through a resistor. The resistor can have a resistance of 1,000 Ohm, 5,000 Ohm, 10,000 Ohm, 50,000 Ohm, 100,000 Ohm, 200,000 Ohm, 250,000 Ohm, 500,000 Ohm, or more. Each portion of the case can be electrically connected, and then the build up of charge on the circuit board through capacitive coupling will be mitigated. The use of a conductive case, for example a conductive plastic or polymer to manufacture housings for use around circuit boards can reduce the likelihood of electrostatic discharge to the circuits of the device. Any charge can be equalized across the case and circuit board, which reduces or eliminates charge polarization which could generate a potential difference that can cause a discharge that can damage components within the device. Referring to FIG. 1, reader 1000 accepts test cartridge 1100 and includes display

1200 and a circuit (not shown) configured to analyze contents of cartridge 1100. Reader 1000 has a case 1700 having an outer surface connected to the ground of the circuit of the reader. A portion of the outer surface of case 1700 is composed of a conductive material. The conductive material has conductivity adequate to dissipate charge buildup on the surface of the device or on the user, which in turn can protect the circuitry from static discharge when a patient touches the device. A portion of the outer surface 1700 contacts an area of the hand of the user during use, grounding the circuit and the user. The grounding improves performance of the reader, including accuracy of the results generated by the reader, and lifetime of the reader by avoiding corruption or destruction of a component of the circuit.

The outer surface can have a conductivity capable of suppressing electrostatic charge build-up on a portion of the device, dissipating charge thereby preventing discharge to or from human contact, or conducting charge. The outer surface can have a resistivity of less than 10¹² ohms per square, less than 10⁹ ohms per square, less than 10⁶ ohms per square, less than 10³ ohms per square or less than less than 10 ohms per square. The outer surface can be composed at least in part of a metal or conductive plastic. The conductive plastic can be surface treated, surface-coated or filled with a conductive material such as metal particles, conductive polymers, carbon fillers, such as carbon particles or carbon fibers, including nanomaterials. The metal can be a foil coating, a vapor deposited coating, a conducting network of metallic particles, or a mesh. For example, the outer surface can include a polypyrrole, carbon black, platinized carbon, a polyaniline, a polythiophene, such as poly(3,4-ethylenedioxythiophene) (PEDOT), PolyOne "Stat-Tech", Semitron® ESd 520HR (polyamide-imide), Semitron® ESd 500HR (PTFE), Semitron® ESd 490HR (polyetheretherketone), Semitron® ESd 480 (polyetheretherketone), Semitron® ESd 420 (polyetherimide), Semitron® ESd 410C (polyetherimide), Tempalux® CN (polyetherimide), Hydel® PEI-7 ESD Ultem (polyetherimide), Carbon-filled PEEK (polyetheretherketone), PES CN (polyethersulfone), PVDF CN (polyvinylidene fluoride), Pomalux® SD & CN (Acetal Copolymer), Semitron® ESd 225 (acetal), Tecaform® SD Acetal, Propylux® SD & CN (polypropylene), Absylux® SD & CN (ABS), Lennite® CN (UHMW polyethylene), Tivar® 1000 Antistatic (UHMW polyethylene), Zelux® SD & CN (polycarbonate), Hydel® PC-7 ESD (polycarbonate), StatiCon® PC-300 & PC-350 (polycarbonate), StatiCon® PVC-300 & PVC-350 (polyvinylchloride), StatiCon® AC-300 & AC-350 (acrylic), or KYDEX® GND (acrylic-PVC alloy). For examples of other materials, see, U.S. Patent No. 6,657,005 Bl, which is incorporated by reference in its entirety.

Reader 1000 can measure the level of an analyte based on, for example, the magnitude of an optical change, an electrical change, or other detectable change that occurs on a test cartridge 1100. For readers that produce an optical change in response to analyte, the reader can include optical systems for measuring the detectable change, for example, a light source, filter, and photon detector, e.g., a photodiode, photomultiplier, or Avalance photo diode. For readers that produce an electrical change in response to analyte, the reader can include electrical systems for measuring the detectable change, including, for example, a voltameter or amperometer.

The display 1200 may be used to display images in various formats, for example, text, joint photographic experts group (JPEG) format, tagged image file format (TIFF), graphics interchange format (GIF), or bitmap. Display 1200 can also be used to display text messages, help messages, instructions, queries, test results, and various information to patients. Display 1200 can provide a user with an input region 1400. Input region 1400 can include keys 1600. In one embodiment, input region 1400 can be implemented as symbols displayed on the display 1200, for example when display 1200 is a touch- sensitive screen. User instructions and queries are presented to the user on display 1200. The user can respond to the queries via the input region.

Device 1000 further can include a communication port (not pictured). The communication port can be, for example, a connection to a telephone line or computer network. Device 1000 can communicate the results of a measurement to an output device, remote computer, or to a health care provider from a remote location.

A patient, health care provider, or other user can use reader 1000 for testing and recording the levels of various analytes, such as, for example, a biomarker, a metabolite, or a drug of abuse. Various implementations of diagnostic device 1000 may access programs and/or data stored on a storage medium (e.g., a hard disk drive (HDD), flash memory, video cassette recorder (VCR) tape or digital video disc (DVD); compact disc (CD); or floppy disk). Additionally, various implementations may access programs and/or data accessed stored on another computer system through a communication medium including a direct cable connection, a computer network, a wireless network, a satellite network, or the like.

The software controlling the reader can be in the form of a software application running on any processing device, such as, a general-purpose computing device, a personal digital assistant (PDA), a special-purpose computing device, a laptop computer, a handheld computer, or a network appliance. The reader may be implemented using a hardware configuration including a processor, one or more input devices, one or more output devices, a computer-readable medium, and a computer memory device. The processor may be implemented using any computer processing device, such as, a general-purpose microprocessor or an application- specific integrated circuit (ASIC). The processor can be integrated with input/output (I/O) devices to provide a mechanism to receive sensor data and/or input data and to provide a mechanism to display or otherwise output queries and results to a service technician. Input device may include, for example, one or more of the following: a mouse, a keyboard, a touch-screen display, a button, a sensor, and a counter.

The display 1200 may be implemented using any output technology, including a liquid crystal display (LCD), a television, a printer, and a light emitting diode (LED). The computer-readable medium provides a mechanism for storing programs and data either on a fixed or removable medium. The computer-readable medium may be implemented using a conventional computer hard drive, or other removable medium. Finally, the system uses a computer memory device, such as a random access memory (RAM), to assist in operating the reader.

Implementations of the reader can include software that directs the user in using the device, stores the results of measurements. The reader 1000 can provide access to applications such as a medical records database or other systems used in the care of patients. In one example, the device connects to a medical records database via the communication port. Device 1000 may also have the ability to go online, integrating existing databases and linking other websites.

In general, the assay device can be made by depositing reagents on a base and sealing a lid over the base. The base can be a micro-molded platform or a laminate platform.

Referring to FIG. 2, reader 1000 includes case 1700. Case 1700 is composed of top 1710 and bottom 1720. At least one of top 1710 or bottom 1720 is conductive. When both top 1710 and bottom 1720 are conductive, a bond 1730 between top 1710 and bottom 1720 is also conductive, for example, made of a conductive adhesive or otherwise forming a conductive contact, which can ensure complete conductive path across surface of case and board. The circuit 1800 of reader 1000 can contain on a printed circuit board. Top 1710 is conductively coupled to the ground plane or power rail of the circuit 1800 by a resistor 1900. Referring to FIG. 3, reader 3000 includes circuit 3800 within housing 3700 having outer surface 3010. Circuit 3800 is configured to read test cartridge 3100 received in an opening 3020 of housing 3700. Circuit 3800 includes an interface 3200 configured to electrically connect at least a portion of the circuitry 3700 with test cartridge 3100 received within the housing 3700. Circuit 3800 also includes detector 3300 configured to determine a signal indicative of the presence of a substance of interest within a sample in test cartridge 3100 received within housing 3700. Circuit 3800 futher includes a processor 3400 in communication with the detector and configured to determine the presence of the substance based at least in part on the signal. In addition, circuit 3800 includes a floating power supply 3600 to provide power to the circuitry 3800. The floating power supply can be a battery or other DC power source. The outer surface 3010 of the housing 3700 has conductive properties and is conductively coupled to the circuitry 3800 such that a likelihood of an electrostatic potential difference between the housing and the circuitry damaging the circuitry is reduced. Examples of assay devices are described, for example, in U.S. Application No. 60/786,363 and PCT Application No. PCT/US2004/042153, each of which is incorporated by reference in its entirety. For example, referring to FIG. 5, assay device base 10 of an assay device includes surface 20. Detection zone 30 and reference zone 40 are disposed on surface 20. First reagent zone 35 overlaps detection zone 30, and second reagent zone 45 overlaps reference zone 40.

In one embodiment, detection zone 30 includes a working electrode, and reference zone 40 includes a reference electrode. First reagent zone 35 includes a redox active enzyme substrate (e.g., glucose) and a redox mediator (e.g., potassium ferricyanide, K₃Fe(CN)₆). Second reagent zone 45 includes a first recognition reagent selected to bind a desired analyte. The first recognition reagent is linked to an enzyme capable of oxidizing or reducing the redox active enzyme substrate. For example, when the redox active enzyme substrate is glucose, the enzyme can be a glucose oxidase (GOD). Second reagent zone 45 can further include a second recognition reagent selected to bind the desired analyte. In particular, the second recognition reagent is selected to bind the desired analyte simultaneously with the first recognition reagent to form a ternary complex.

Referring to FIG. 4, assembled assay device 100 includes base 10 separated from lid 50 by spacers 60. Spacers 60 can be formed as an integral part of base 10 or lid 50. Alternatively, base 10, lid 50 and spacers 60 can be formed separately and assembled together. When assembled, together, connections between base 10, lid 50 and spacers 60 can be sealed, for example with an adhesive or by welding. Base 10, lid 50 and spacers 60 can define a liquid-tight volume 70 where a liquid sample is allowed to contact interior surfaces of volume 70, such as surface 20 of base 10. The dimensions of spacer 60 can be selected such that surfaces of base 10 and Hd 50 facing the interior of volume 70 form a capillary, i.e., the base and lid provide capillary action to a liquid inside volume 70. Alternatively, base 10 or lid 50 can provide capillary action independently of each other. Volume 70 can have a volume of less than 100 microliters, less than 20 microliters, less than 10 microliters, or 5 microliters or less. Other embodiments are within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. A device comprising: a housing having an outer surface, an opening within the housing to receive a test member, circuitry within the housing, comprising: an interface configured to electrically connect at least a portion of the circuitry with a test member received within the housing, a detector configured to determine a signal indicative of the presence of a substance of interest within a sample in a test member received within the housing, a processor in communication with the detector and configured to determine the presence of the substance based at least in part on the signal, and a floating power supply to provide power to the circuitry; wherein the outer surface of the housing has conductive properties and is conductively coupled to the circuitry such that a likelihood of an electrostatic potential difference between the housing and the circuitry damaging the circuitry is reduced.

2. The device of claim 1, wherein the outer surface of the housing comprises conductive polymer or metal.

3. The device of claim 1 , wherein the housing is comprised of conductive polymer or metal.

4. The device of claim 3, wherein the conductive polymer is selected from the group consisting of polypyrrole, polythiophene, polyaniline, carbon black, and platinized carbon.

5. The device of claim 3, wherein the metal comprises a foil coating, a vapor deposited coating, a conducting network of metallic particles, or a mesh.

6. The device of claim 1, wherein the housing comprises at least a first portion and a second portion.

7. The device of claim 6, wherein each of the first and second portions of the housing are conductively coupled to the circuitry by a resistor.

8. The device of claim 7, wherein the resistor that makes a connection between the conductive casing material and the circuitry has resistivity of less than 10¹² ohms per square.

9. The device of claim 7, wherein the resistor that makes a connection between the conductive casing material and the circuitry has resistivity of less than 10⁹ ohms per square.

10. The device of claim 7, wherein the resistor that makes a connection between the conductive casing material and the circuitry has resistivity of less than 10⁶ ohms per square.

11. The device of claim 7, wherein the resistor that makes a connection between the conductive casing material and the circuitry has resistivity of less than 10³ ohms per square.

12. The device of claim 7, wherein the resistor that makes a connection between the conductive casing material and the circuitry has resistivity of less than 10 ohms per square.

13. The device of claim 1, wherein the detector is an electrochemical detector.

14. The device of claim 13, wherein the detector is in electrical communication with the test member via the interface.

15. The device of claim 1, wherein the processor is configured to receive a signal from the detector and produce a response.

16. The device of claim 1, wherein the floating power supply is a battery.

17. The device of claim 1, wherein the floating power supply is an isolation transformer.

18. The device of claim 1, wherein the circuitry is not configured to receive electrical current from an electrical current source external to the housing.

19. The device of claim 1, wherein the device is not configured to operably receive energy from an energy source external to the housing.

20. The device of claim 1 , wherein the power supply is inductively coupled to an external power supply.

21. A method, comprising: manually manipulating a conductive outer surface of a housing of an assay device, inserting a test member into an opening of the device, introducing a biological sample to the test member, and operating circuitry of the device to determine the presence of an analyte within the biological sample and display a result indicative of the presence of the analyte, the circuitry being powered by a floating power supply internal to the housing, wherein: at least one of the steps of manually manipulating and inserting comprises reducing or preventing an electrical potential difference between the surface of the housing and the circuitry.

22. A method of measuring a substance in a sample comprising: a user making contact with a device, for example holding the device, such that the device and circuitry within the device become equipotential with the user; inserting a test member into the device; applying a sample to the test member; and presenting a measurement response to a user.

23. The method of claim 22, wherein the device includes: a housing having an outer surface, a circuitry within the housing, comprising at least; a detector, a processor, an interface for a test member, a floating power supply to provide power to the circuit; and an opening within the housing to receive a test member, wherein the housing has conductive properties and is conductively coupled to the circuit such that build up of an electrostatic potential difference between the housing and the circuit is does not occur.

24. The method of claim 22, wherein the outer surface comprises conductive polymer or metal.

25. The method of claim 22, wherein the housing includes a conductive polymer top, a conductive polymer bottom, or both.

26. The method of claim 22, wherein the housing is conductively coupled to the casing by a resistor.

27. The method of claim 22, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10¹² ohms per square.

28. The method of claim 22, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10⁹ ohms per square.

I l

29. The method of claim 22, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10⁶ ohms per square.

30. The method of claim 22, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10³ ohms per square.

31. The method of claim 22, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10 ohms per square.

32. A device for measuring an analyte in a sample obtained from a patient comprising: a housing having an outer surface; and a circuit contained within the housing, wherein the outer surface is conductive and is conductively coupled to the circuit.

33. The device of claim 32, wherein the outer surface comprises conductive plastic or metal.

34. The device of claim 32, wherein the housing includes a conductive plastic top, a conductive plastic bottom, or both.

35. The device of claim 32, wherein the housing is electrically coupled to the casing by a resistor.

36. The device of claim 35, wherein the resistor is at least a 1,000 Ohm resistor.

37. A system for measuring an analyte in a sample comprising: a device comprising: a housing having an outer surface; and a circuit contained within the housing, wherein the outer surface is conductive and is conductively coupled to the circuit.

38. The system of claim 37, wherein the outer surface comprises conductive plastic or metal.

39. The system of claim 37, wherein the housing includes a conductive plastic top, a conductive plastic bottom, or both.

40. The system of claim 37, wherein the housing is electrically coupled to the casing by a resistor.

41. The system of claim 40, wherein the resistor is at least a 1,000 Ohm resistor.

42. A method of measuring an analyte in a sample comprising: touching the device in a manner sufficient to dissipate surface charges on the device or a user; and applying the sample to the device.

43. The method of claim 42, wherein the device includes: a housing having an outer surface; and a circuit contained within the housing, wherein the outer surface is conductive and conductively couples to the circuit.

44. The method of claim 42, wherein the outer surface comprises conductive plastic or metal.

45. The method of claim 42, wherein the housing includes a conductive plastic top, a conductive plastic bottom, or both.

46. The method of claim 42, wherein the housing is electrically coupled to the casing by a resistor.

47. The method of claim 42, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10¹² ohms per square.

48. The method of claim 42, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10⁹ ohms per square.

49. The method of claim 42, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10⁶ ohms per square.

50. The method of claim 42, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10³ ohms per square.

51. The method of claim 42, wherein the resistor that makes a connection between the conductive casing material and the circuit has resistivity of less than 10 ohms per square.