Method and device for compensating temperature-dependent characteristic changes in ion-sensitive FET transducer
First Claim
1. An ion activity monitoring device which comprises:
- a semi-conductor device including,an ion-sensitive field-effect transistor for detecting the activity of ions in a liquid medium of interest, and developing an ion activity signal indicative thereof, anda temperature sensor for detecting the temperature of the liquid medium of interest and developing a temperature signal indicative thereof;
a constant current circuit for supplying to the ion-sensitive field-effect transistor a drain current satisfying the following relationship;
space="preserve" listing-type="equation">|Id/β
|≦
0.10 volt.sup.2 wherein Id represents the drain current and β
represents the channel characteristic value of the ion-sensitive field-effect transistor during the operation thereof; and
a processing circuit, responsive to both the ion activity signal from the ion-sensitive field-effect transistor and the temperature signal from the temperature sensor, for calculating the concentration of the ions in the liquid medium of interest, said processing circuit including,temperature zero-adjustment compensating means for effecting a zero adjustment to the ion activity signal from the ion-sensitive field-effect transistor, and a zero adjustment to the temperature, signal from the temperature sensor, andtemperature sensitivity compensating means for adjusting the sensitivity of the monitoring device to the ion activity, based on both the ion activity signal and the temperature signal.
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Accused Products
Abstract
An ion activity monitoring device is disclosed, having a semi-conductor device including an ion-sensitive field-effect transistor, for detecting the activity of ions in a liquid medium of interest, and a temperature sensor, for detecting the temperature of the liquid medium of interest, a constant current circuit for supplying a drain current of a particular value to the transistor, and a processing circuit for calculating the concentration of the ions in the liquid medium of interest. The drain current is of a value satisfying the relationship of |Id/β|≦0.10 volt2, wherein Id represents the drain current and β represents the channel characteristic value of the ion-sensitive field-effect transistor. A method for operating the transistor is also disclosed.
53 Citations
9 Claims
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1. An ion activity monitoring device which comprises:
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a semi-conductor device including, an ion-sensitive field-effect transistor for detecting the activity of ions in a liquid medium of interest, and developing an ion activity signal indicative thereof, and a temperature sensor for detecting the temperature of the liquid medium of interest and developing a temperature signal indicative thereof; a constant current circuit for supplying to the ion-sensitive field-effect transistor a drain current satisfying the following relationship;
space="preserve" listing-type="equation">|Id/β
|≦
0.10 volt.sup.2wherein Id represents the drain current and β
represents the channel characteristic value of the ion-sensitive field-effect transistor during the operation thereof; anda processing circuit, responsive to both the ion activity signal from the ion-sensitive field-effect transistor and the temperature signal from the temperature sensor, for calculating the concentration of the ions in the liquid medium of interest, said processing circuit including, temperature zero-adjustment compensating means for effecting a zero adjustment to the ion activity signal from the ion-sensitive field-effect transistor, and a zero adjustment to the temperature, signal from the temperature sensor, and temperature sensitivity compensating means for adjusting the sensitivity of the monitoring device to the ion activity, based on both the ion activity signal and the temperature signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification