On-chip cell migration detection

• US 8,779,779 B2
• Filed: 10/24/2008
• Issued: 07/15/2014
• Est. Priority Date: 04/08/2008
• Status: Active Grant

• Current Assignee: CapitalBio Corporation, Tsinghua University
• Original Assignee: CapitalBio Corporation, Tsinghua University
• Inventors: Wang, Lei, Zhu, Jing, Deng, Cheng, Cheng, Jing
• Primary Examiner(s): Vazquez, Arleen M
• Assistant Examiner(s): LE, SON T
• Application Number:
  US12/288,971
• Publication Number:
  US 20090251155A1
• Time in Patent Office: 2,090 Days
• Field of Search: 324/688, 324/649, 435/287.1, 435/32, 435/401, 435/288.5, 435/297.5, 435/173.1, 435/173.4, 435/286.1
• US Class Current: 324/649
• CPC Class Codes: B01L 2200/10 Integrating sample preparation and analysis in single entity, e.g. lab-on-a-chip concept
• CPC Class Codes: B01L 2200/12 Specific details about manufacturing devices
• CPC Class Codes: B01L 2300/0636 Integrated biosensor, microarrays
• CPC Class Codes: B01L 2300/0645 Electrodes
• CPC Class Codes: B01L 2300/069 Absorbents; Gels to retain a fluid
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/16 Surface properties and coatings
• CPC Class Codes: B01L 3/502761 specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads, for physically stretching molecules investigating characteristics of particles G01N15/00
• CPC Class Codes: G01N 33/4836 using multielectrode arrays
• CPC Class Codes: G01N 33/5029 on cell motility
• CPC Class Codes: G01N 33/5438 Electrodes

Abstract

Techniques, systems and apparatus are disclosed for detecting impedance. In one aspect, a microelectrode sensing device includes a substrate and an array of microelectrode sensors formed on the substrate. Each sensor includes at least one conductive layer formed above the substrate and patterned to include a counter electrode and multiple sensing electrodes to detect an electrical signal in absence and presence of one or more target cells positioned on at least a portion of a surface of each sensing electrode. The sensing electrodes are spaced apart and arranged around the counter electrode to provide a spatially averaged value of the detected electrical signal.

Claims

1. A microelectrode sensing device, comprising:

a substrate;

an array of microelectrode sensors formed on the substrate, each sensor comprising at least one conductive layer formed above the substrate and patterned to comprise a counter electrode and a plurality of sensing electrodes to detect an electrical signal in absence and presence of one or more target cells positioned on at least a portion of a surface of each sensing electrode; and

a chemical coating on a first region of the surface of each of the plurality of sensing electrodes to inhibit adhesion of the one or more target cells onto the first region of the surface of the plurality of sensing electrodes, while a second region of the surface of each of the plurality of sensing electrodes is free of the chemical coating to allow adhesion of the one or more target cells onto the second region of the surface of the plurality of sensing electrodes, and wherein the chemical coating is made of a material that desorbs from the surface of the plurality of sensing electrodes in response to an electrical stimulus;

wherein the plurality of sensing electrodes are spaced apart and arranged around the counter electrode and each sensing electrode having one end facing the counter electrode and a second end facing away from the counter electrode, the second end commonly connected to second ends of all other sensing electrodes to collectively provide a single spatially averaged output value of the detected electrical signal, and

wherein the first region of the surface of each sensing electrode is located at the end of each sensing electrode facing the counter electrode, and

wherein the second region of the surface of each sensing electrode is adjacent to the first region and extended to the second end of each sensing electrode.

2. The microelectrode sensing device of claim 1, wherein the plurality of sensing electrodes comprise a plurality of concentric sensing electrodes.

3. The microelectrode sensing device of claim 1, comprising one or more layers of insulating material formed between the plurality of sensing electrodes to electrically insulate the plurality of sensing electrodes from each another.

4. The microelectrode sensing device of claim 1, wherein the at least one conductive layer is patterned to comprise the counter electrode and the plurality of sensing electrodes in a ratio of 1 counter electrode to N sensing electrodes, where N is a positive integer.

5. The microelectrode sensing device of claim 1, wherein the at least one conductive layer is patterned to comprise the counter electrode and the plurality of sensing electrodes so as to provide a total surface area of the counter electrode that is at least twice a total surface area of the plurality of sensing electrodes.

6. The microelectrode sensing device of claim 1, wherein the at least one conductive layer is patterned to comprise the counter electrode and the plurality of sensing electrodes to detect a change in the electrical signal in response to the one or more target cells migrating onto the surface of the plurality of sensing electrodes from an area outside of the surface of the sensing electrodes.

7. The microelectrode sensing device of claim 1, wherein the at least one conductive layer is patterned to comprise the counter electrode and the plurality of sensing electrodes to detect an impedance to a flow of the electrical signal in response to the one or more target cells migrating onto the surface of the sensing electrodes from an area outside of the surface of the sensing electrodes.

8. The microelectrode sensing device of claim 1, wherein the chemical coating comprises a self-assembled monolayer or bi-layer.

9. The microelectrode sensing device of claim 1, wherein the plurality of sensing electrodes comprise sensing electrodes arranged to form a concentric shape around the counter electrode located at a center of the concentric shape.

10. The microelectrode sensing device of claim 9, wherein the plurality of sensing electrodes are at an equal distance away from each other.

11. The microelectrode sensing device of claim 1, wherein each sensing electrode is at an equal radial distance away from a center of the counter electrode.

12. The microelectrode sensing device of claim 1, wherein the plurality of sensing electrodes are symmetrical in shape and similarly sized to provide uniform impedance measurement from one electrode to another.

13. A system comprising:

a microelectrode sensing device comprising;

a substrate, and

an array of microelectrode sensors formed on the substrate, each sensor comprising at least one conductive layer formed above the substrate and patterned to comprise a counter electrode and a plurality of sensing electrodes to detect an electrical signal in absence and presence of one or more target cells positioned on at least a portion of a surface of each sensing electrode,

wherein the plurality of sensing electrodes are spaced apart, arranged around the counter electrode such that one end of each electrode is collectively connected to end of a common output to provide a single spatially averaged output value of the detected electrical signal; and

an analysis system in communication with the microelectrode sensing device to

receive from the microelectrode sensing device data representing at least the electrical signal detected by the sensing electrodes, and

process the received data to obtain one or more impedance measurements;

wherein the microelectrode sensing device comprises a chemical coating on a first region of the surface of each of the plurality of sensing electrodes to inhibit adhesion of the one or more target cells onto the first region of the surface of the plurality of sensing electrodes, while a second region of the surface of each of the plurality of sensing electrodes is free of the chemical coating to allow adhesion of the one or more target cells onto the second region of the surface of the plurality of sensing electrodes, and wherein the chemical coating is made of a material that desorbs from the surface of the plurality of sensing electrodes in response to an electrical stimulus, and

wherein the first region of the surface of each sensing electrode is located at a second end of each sensing electrode facing the counter electrode, and

wherein the second region of the surface of each sensing electrode is adjacent to the first region and extended to the second end of each sensing electrode.

14. The system of claim 13, wherein the analysis system is configured to receive the data representing at least the electrical signal detected by the sensing electrodes in absence of the target cells to establish a control impedance measurement.

15. The system of claim 14, wherein the analysis system is configured to receive in real-time, the data representing at least the electrical signal detected by the sensing electrodes over a period of time corresponding to migration of the one or more target cells onto the surface of the sensing electrodes from a location external to the surface.

16. The system of claim 15, wherein the analysis system is configured to process the data received in absence of target cells and the data received over the period of time corresponding to migration of the one or more target cells to identify a change in impedance corresponding to the migration of the one or more target cells.

17. The system of claim 13, wherein the chemical coating comprises a self-assembled monolayer or bi-layer.

18. The system of claim 13, wherein the analysis system is configured to apply the electrical stimulus to the sensing electrodes to desorb the chemical coating.

19. A method for monitoring cell migration comprising:

applying a chemical coating layer on a first region of a surface of each sensing electrode in a microelectrode sensing device that includes a counter electrode and a plurality of sensing electrodes to inhibit adhesion of target cells on the first region of the surface of each sensing electrode, while a second region of the surface of each of the plurality of sensing electrodes is free of the chemical coating to allow adhesion of the one or more target cells onto the second region of the surface of the plurality of sensing electrodes;

seeding the target cells in the microelectrode sensing device to allow the seeded target cells to adhere to areas outside of the surface of each sensing electrode;

applying an electrical signal to each sensing electrode to desorb the applied chemical coating layer from the surface of each sensing electrode;

detecting a change in an electrical impedance measured by each sensing electrode in response to one or more of the seeded target cells migrating onto the surface of each sensing electrode; and

receiving a single spatially averaged output value of a detected electrical signal from the plurality of sensing electrode, wherein the plurality of sensing electrodes are spaced apart and arranged around the counter electrode and connected to one another to provide the single spatially averaged output value,

wherein the first region of the surface of each sensing electrode is located at one end of each sensing electrode facing the counter electrode, and

wherein the second region of the surface of each sensing electrode is adjacent to the first region and extended to the second end of each sensing electrode.

20. The method of claim 19, wherein applying the chemical coating comprises applying a layer of thiol based compound.

21. The method of claim 19, further comprising applying the chemical coating on a surface of the counter electrode in the microelectrode sensing device.

22. The method of claim 19, wherein applying the chemical coating comprise applying one or more self-assembled monolayers.

23. The method of claim 19, comprising measuring a background impedance value before seeding the target cells.

24. The method of claim 23, comprising calculating a normalized impedance value based on the background impedance value.

25. The method of claim 19, comprising detecting the change in the electrical impedance in real time as the one or more of the seeded target cells migrate onto the surface of each sensing electrode until a steady state impedance is reached.

26. The method of claim 19, wherein detecting the change in the electrical impedance measured by each sensing electrode comprises applying another electrical signal to each sensing electrode.

27. The Method of claim 26, wherein applying the other electrical signal comprises in response to the other electrical signal applied to each sensing electrode, receiving a sensed signal from each sensing electrode and averaging the sensed signals to obtain an average impedance measurement due to the one or more of the seeded target cells migrate onto the surface of each sensing electrode.

28. The method of claim 27, comprising determining a speed of cell migration based on the obtained average impedance measurement.

29. The method of claim 19, comprising arranging the plurality of sensing electrodes in a concentric shape around the counter electrode.