METHOD OF DETERMINING A SENSITIVITY OF A BIOSENSOR ARRANGEMENT, AND BIOSENSOR SENSITIVITY DETERMINING SYSTEM

• US 20110062972A1
• Filed: 09/09/2010
• Published: 03/17/2011
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Agency For Science Technology and Research (Government of Singapore)
• Original Assignee: Agency For Science Technology and Research (Government of Singapore)
• Inventors: Je, Minkyu, Zhang, Guo-Jun, Chai, Tshun Chuan, Fang, Cheng
• Granted Patent: US 8,860,442 B2
• Time in Patent Office: Days
• US Class Current: 324/692
• CPC Class Codes: G01N 27/4145 specially adapted for biomolecules, e.g. gate electrode with immobilised receptors

Abstract

According to an embodiment of the present invention, a method of determining or adjusting the sensitivity of a biosensor arrangement comprising at least one field effect biosensor is provided, each of the at least one field effect biosensor comprising: a semiconductor substrate comprising a source region, a drain region and a channel region disposed between the source region and the drain region; a gate isolation layer covering the channel region; and a reference electrode disposed over the gate isolation layer such that a electrolytic solution to be sensed can be provided between the reference electrode and the gate isolation layer. The method comprises the following processes carried out for each field effect biosensor: providing an electrolytic solution between the reference electrode and the gate isolation layer; applying a source/drain voltage between the source region and the drain region; varying a reference voltage supplied to the reference electrode over a voltage range; measuring a resulting drain current while varying the reference voltage in order to obtain a corresponding drain current function; and determining the sensitivity of the field effect biosensor based on the reference voltage supplied to the reference electrode and the corresponding drain current function.

Claims

1. A method of determining/adjusting the sensitivity of a biosensor arrangement comprising at least one field effect biosensor, each of the at least one field effect biosensor comprising:

a semiconductor substrate comprising a source region, a drain region and a channel region disposed between the source region and the drain region;

a gate isolation layer covering the channel region; and

a reference electrode disposed over the gate isolation layer such that a electrolytic solution to be sensed can be provided between the reference electrode and the gate isolation layer,

the method comprising the following processes carried out for each field effect biosensor;

providing an electrolytic solution between the reference electrode and the gate isolation layer;

applying a source/drain voltage between the source region and the drain region;

varying a reference voltage supplied to the reference electrode over a voltage range;

measuring a resulting drain current while varying the reference voltage in order to obtain a corresponding drain current function; and

determining the sensitivity of the field effect biosensor based on the reference voltage supplied to the reference electrode and the corresponding drain current function.

2. The method according to claim 1,

wherein determining the sensitivity of a field effect biosensor comprises:

determining an effective transconductance function by differentiating the measured drain current function with respect to the reference voltage supplied;

dividing the determined effective transconductance function by the measured drain current function.

3. The method according to claim 1,

further comprising comparing the sensitivities of the different field effect biosensors among each other, wherein a normalization process is carried out in which an average sensitivity for all of the field effect biosensors is calculated.

4. The method according to claim 1,

further comprising shifting the working point of each field effect biosensor into a region of maximum sensitivity.

5. The method according to claim 1,

further comprising shifting the working point of each field effect biosensor into a region of increased sensitivity in which the sensitivity is not maximum, in which however the drain current would still be large enough to yield reliable measurement results.

6. The method according to claim 1,

further comprising comparing the sensitivities of the field effect biosensors among each other, wherein biosensors showing a sensitivity falling below a first threshold value or exceeding a second threshold value are disabled.

7. A biosensor sensitivity determining system for determining/adjusting the sensitivity of a biosensor arrangement comprising at least one field effect biosensor, each of the at least one field effect biosensor comprising:

a semiconductor substrate comprising a source region, a drain region and a channel region disposed between the source region and the drain region;

a gate isolation layer covering the channel region; and

a reference electrode disposed over the gate isolation layer such that a electrolytic solution to be sensed can be provided between the reference electrode and the gate isolation layer,

the biosensor sensitivity determining system comprising the following functional units for each of the field effect biosensors;

a source/drain voltage applying unit adapted to apply a source/drain voltage between the source region and the drain region;

a reference voltage applying unit adapted to apply a varying reference voltage which varies over a predetermined voltage range to the reference electrode;

a drain current measuring unit adapted to measure a drain current resulting when varying the reference voltage in order to obtain a corresponding drain current function; and

a sensitivity determining unit adapted to determine the sensitivity based on the reference voltage supplied to the corresponding reference electrode and the corresponding drain current function.

8. The biosensor sensitivity determining system according to claim 7,

wherein the sensitivity determining unit is further adapted to:

determine an effective transconductance function by differentiating the measured drain current function with respect to reference voltage supplied to the reference electrode;

dividing the determined effective transconductance function by the measured drain current function.

9. The biosensor sensitivity determining system according to claim 7, further comprising a processing unit adapted to compare the sensitivities of the field effect biosensors among each other, wherein a normalization process is carried out in which an average sensitivity for all of the field effect biosensors is calculated.

10. The biosensor sensitivity determining system according to claim 7, further comprising a calibration unit adapted to shift the working point of each field effect biosensor into a region of maximum sensitivity.

11. The biosensor sensitivity determining system according to claim 7,

further comprising a calibration unit adapted to shift the working point of each field effect biosensor into a region of increased sensitivity in which the sensitivity is not maximum, in which however the drain current would still be large enough to yield reliable measurement results.

12. The biosensor sensitivity determining system according to claim 7, further comprising a disabling unit adapted to compare the sensitivities of the field effect biosensors among each other, wherein biosensors showing a sensitivity falling below a first threshold value or exceeding a second threshold value are disabled.