Sensor cell
First Claim
1. A sensor cell comprising a thin film transistor, a reference capacitor coupled to a gate electrode of the thin film transistor, a sample electrode coupled to the gate electrode of the thin film transistor and arranged to receive a sample for identification, the reference capacitor and the sample electrode providing in combination, a capacitance divider circuit coupled to the gate electrode of the thin film transistor, a further transistor for affording a voltage pulse to the gate electrode of the thin film transistor, the voltage pulse having an amplitude arranged to maintain the thin film transistor in a non-conducting condition and to bias the thin film transistor to a point on its operating characteristic where it is ready to switch from the non-conducting condition to a conducting condition;
- and means for providing an excitation pulse to the gate electrode of the thin film transistor via the capacitance divider circuit, thereby to switch the thin film transistor from the non-conducting condition at the point on its operating characteristic to a conducting condition, whereby in use of the sensor cell, the output current of the thin film transistor is dependent upon the value of capacitance at the sample electrode arising from receiving the sample for identification.
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Accused Products
Abstract
A sensor cell comprises receiving means, which may be in the form of an electrode 10 coupled to the gate electrode of a thin film transistor T1. In one form of the invention a voltage supplied to the gate electrode of the transistor T1 via a switching transistor T7 is controlled in dependence upon the value of capacitance CA arising at the electrode from receipt of a sample for identification. Thus, the operation of transistor T1 can be used to identify the sample received by the electrode 10.
114 Citations
49 Claims
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1. A sensor cell comprising a thin film transistor, a reference capacitor coupled to a gate electrode of the thin film transistor, a sample electrode coupled to the gate electrode of the thin film transistor and arranged to receive a sample for identification, the reference capacitor and the sample electrode providing in combination, a capacitance divider circuit coupled to the gate electrode of the thin film transistor, a further transistor for affording a voltage pulse to the gate electrode of the thin film transistor, the voltage pulse having an amplitude arranged to maintain the thin film transistor in a non-conducting condition and to bias the thin film transistor to a point on its operating characteristic where it is ready to switch from the non-conducting condition to a conducting condition;
- and means for providing an excitation pulse to the gate electrode of the thin film transistor via the capacitance divider circuit, thereby to switch the thin film transistor from the non-conducting condition at the point on its operating characteristic to a conducting condition, whereby in use of the sensor cell, the output current of the thin film transistor is dependent upon the value of capacitance at the sample electrode arising from receiving the sample for identification.
- View Dependent Claims (4, 5, 7, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 34, 35)
- 2. A sensor cell comprising a thin film transistor, a sample electrode coupled to the gate electrode of the thin film transistor and arranged to receive a sample for identification, a switching transistor coupled to the gate electrode of the thin film transistor and arranged to switch between a non-conducting condition and a conducting condition to enable a voltage to be selectively provided to the grate electrode of the thin film transistor for selectively switching the thin film transistor between a non-conducting condition and conducting condition, thereby when the switching transistor is switched to the non-conducting condition, the voltage provided at the gate electrode of the thin film transistor is arranged to decrease in magnitude in a time dependent manner and thereby cause the thin film transistor to switch from a conducting to a non-conducting condition, the time taken between the switching of the switching transistor and the switching of the thin film transistor between their respective conducting and non-conducting conditions being dependent upon the value of capacitance at the sample electrode.
- 3. A method of identifying a sample comprising applying the sample to a sensor cell having a sample electrode arranged in combination with a reference capacitor as a capacitance divider circuit coupled to a gate electrode of a thin film transistor, providing a voltage pulse to the gate electrode of the thin film transistor when in a non-conducting condition, the voltage pulse being arranged to have a magnitude such that the thin film transistor remains in the non-conducting condition and is biased to a point on its operating characteristic where it is ready to switch from the non-conducting condition to a conducting condition, and providing an excitation pulse to the gate electrode of the thin film transistor via the capacitance divider circuit, thereby to switch the thin film transistor from the non-conducting condition at the point on its operating characteristic to the conducting condition, and measuring the output current of the thin film transistor in the conducting condition.
- 38. A method of identifying a sample comprising applying the sample to a sensor cell having a sample electrode for receiving the sample, a thin film transistor having a gate electrode coupled to the sample electrode, and a switching transistor coupled to the gate electrode and arranged to switch between a non-conducting and a conducting condition, the method comprising providing a voltage to the gate electrode of the thin film transistor by switching the switching transistor to its conducting condition thereby to place the thin film transistor in a conducting condition, switching the switching transistor from its conducting condition to its non-conducting condition, thereby to cause the voltage provided to the gate electrode of the thin film transistor to decrease in magnitude in a time dependent manner and cause the thin film transistor to switch from the conducting condition to a non-conducting condition, the time taken between the switching of the switching transistor and the switching of the thin film transistor between their respective conducting and non-conducting conditions being dependent upon the value of capacitance at the sample electrode.
Specification