Method for feedback control of a microfluidic system

• US 20050266571A1
• Filed: 07/28/2005
• Published: 12/01/2005
• Est. Priority Date: 03/26/2004
• Status: Abandoned Application

• Current Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Original Assignee: LifeScan Scotland Limited (Johnson & Johnson)
• Inventors: Lillie, Geoffrey, Stout, Phil, Moffat, James
• Application Number:
  US11/193,704
• Publication Number:
  US 20050266571A1
• Time in Patent Office: Days
• US Class Current: 436/55
• CPC Class Codes: A61B 5/14514 using means for aiding extraction of interstitial fluid, e.g. microneedles or suction
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: B01L 2200/143 Quality control, feedback systems
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/0803 Disc shape
• CPC Class Codes: B01L 2300/0806 Standardised forms, e.g. compact disc [CD] format
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2400/0409 centrifugal forces
• CPC Class Codes: B01L 2400/0638 membrane valves, flap valves
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: G01N 27/3271 Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001
• CPC Class Codes: Y10T 436/12 Condition responsive control

Abstract

A method for the feedback control of a microfluidic system includes measuring an electrical characteristic (such as impedance or resistance) of a position electrode(s) of the microfluidic system with a meter of the microfluidic system. A feedback controller is then employed to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter.

Claims

1. A method for the feedback control of a microfluidic system, the method comprising:

measuring an electrical characteristic of at least one position electrode of a microfluidic system with a meter of the microfluidic system, the microfluidic system including;

an analysis module with

at least one micro-channel for receiving and transporting a bodily fluid sample;

at least one analyte sensor for measuring an analyte in the bodily fluid sample, each of the at least one analyte sensors being in operative communication with a micro-channel; and

the at least one position electrode, each of the at least one position electrodes in operative communication with at least one micro-channel;

a sampling module configured to extract the bodily fluid sample from a target site of a user'"'"'s body and transport the bodily fluid sample to the at least one micro-channel;

a meter configured for measuring an electrical characteristic of the at least one position electrode, the electrical characteristic being dependent on a position of the liquid sample in the micro-channel in operative communication with the at least one position electrode for which an electrical characteristic is measured; and

a feedback controller adapted to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter; and

employing the feedback controller to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter.

2. The method of claim 1, wherein the measuring step measures an impedance of the at least one position electrode.

3. The method of claim 1, wherein the measuring step measures a resistance of the at least one position electrode.

4. The method of claim 1, wherein the employing step employs the feedback controller to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter that is indicative of a position of the bodily fluid sample.

5. The method of claim 1, wherein the employing step employs the feedback controller to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter that is indicative of a flow rate of the bodily fluid sample.

6. The method of claim 1, wherein the employing step employs the feedback controller to control the flow of bodily fluid sample through the microfluidic system based on the electrical characteristic measured by the meter that is indicative of a volume of the bodily fluid sample.

7. The method of claim 1, wherein the employing step employs the feedback controller to control the flow of bodily fluid sample through the microfluidic system by placing a pressure ring of the sampling module in at least one of a retracted state and a deployed state.

8. The method of claim 1, wherein the employing step employs the feedback controller to control the flow of bodily fluid sample through the microfluidic system by placing a membrane valve of the analysis module in at least one of a deformed condition and an undeformed condition.

9. The method of claim 1, wherein the bodily fluid sample is an interstitial fluid (ISF) sample.

10. The method of claim 1, wherein the measuring step measures the electrical characteristic employing an electrical signal with a frequency in the range of from about 10 Hz to about 100 kHz and a voltage waveform symmetrical around 0 Volts.

11. The method of claim 1, wherein the feedback controller controls the flow of bodily fluid sample through the microfluidic system based to facilitate semi-continuous stopped flow measurements of an analyte in the bodily fluid sample by the analyte sensor.