Sensor for measuring an ion concentration or gas concentration
First Claim
1. Sensor for measuring an ion concentration or a gas concentration with a sensitive layer (6) whose potential depends on a surrounding gas concentration or ion concentration, with the sensitive layer (6) having a first sensitive partial area (20) and a second sensitive partial area (21), a first conductive area (1b) that is capacitively coupled by a first air gap (9) with first sensitive partial area (20), a second conductive area (2b) coupled capacitively through a second air gap (10) with second sensitive partial area (21), with the capacitances of the two capacitive couplings being different, a comparison circuit (1a, 2a, 3, 4, 5) which has at least a first transistor (T1) connected with the first conducting area, and a second transistor (T2) connected with the second conducting area, and at least one output from which a signal can be tapped, depending on the potential of sensitive layer (6).
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Accused Products
Abstract
The invention relates to a sensor for measuring ion concentration or gas concentration, with a gas- or ion-sensitive layer (6) that has two sensitive partial areas (20 and 21), two conducting areas (1b and 2b), each coupled capacitively through air gaps (9and 10) with one of the sensitive partial areas (20 and 21), with the capacitances of the couplings being different, and a comparison circuit (1a, 2a, 3, 4, 5) which has at least one first transistor (T1) connected with the first conductive area and a second transistor (T2) connected with the second conductive area, and at least one output at which a signal can be tapped that depends on the potential of sensitive layer (6).
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Citations
16 Claims
- 1. Sensor for measuring an ion concentration or a gas concentration with a sensitive layer (6) whose potential depends on a surrounding gas concentration or ion concentration, with the sensitive layer (6) having a first sensitive partial area (20) and a second sensitive partial area (21), a first conductive area (1b) that is capacitively coupled by a first air gap (9) with first sensitive partial area (20), a second conductive area (2b) coupled capacitively through a second air gap (10) with second sensitive partial area (21), with the capacitances of the two capacitive couplings being different, a comparison circuit (1a, 2a, 3, 4, 5) which has at least a first transistor (T1) connected with the first conducting area, and a second transistor (T2) connected with the second conducting area, and at least one output from which a signal can be tapped, depending on the potential of sensitive layer (6).
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15. Method for making a sensor, in which an insulating layer (7, 8), preferably a thick oxide layer, is formed on a substrate (11) of a first charge carrier type in a first section (17) and in a separate second section (18), separated lengthwise, at least two drain areas (3, 4) and a source area (5) of a second charge carrier type are formed preferably by ion implantation between which a thin oxide layer is applied, a first and second conductive layer (1, 2) are each applied to insulating layers (7, 8) and the thin oxide layer in such a way that two conductive areas (1b, 2b) are formed in the first section above the insulating layer and two gates (1a, 2a) are formed in a second section, at least two air gaps (9, 10) are formed between insulating intermediate layers (13, 15), and a sensitive layer (6) is applied to the intermediate layers in such a way that air gaps (9 and 10) are formed between two partial areas (20, 21) of sensitive layer (6) and conducting areas (1b and 2b).
Specification