# US 2002/0117693 A1 · Odor sensor with organic transistor circuitry

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- Number: US 2002/0117693 A1
- Document ID: US20020117693A1
- Status: Published application
- Kind: A1
- Application number: 09/793,050
- Filed: 2001-02-26
- Published: 2002-08-29
- Earliest claimed: 2001-02-26
- Assignees: Lucent Technologies Inc.
- Inventors: Ananth Dodabalapur; Alan Gelperin; Howard Edan Katz
- Web page: https://patentgrep.com/patent/US20020117693A1

## CPC

- G01N 27/4141: {specially adapted for gases}
- G01N 27/4148: {Integrated circuits therefor, e.g. fabricated by CMOS processing}
- H10K 19/80: Interconnections, e.g. terminals
- H10K 10/466: {Lateral bottom-gate IGFETs comprising only a single gate}
- H10K 19/20: comprising components having an active region that includes an inorganic semiconductor
- H10K 85/113: {Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene}
- H10K 85/311: {Phthalocyanine}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES

## Abstract

Circuits include at least one-odor sensitive organic transistor having a conduction channel whose conductivity changes in response to certain odors. The organic transistors are interconnected to increase their response to selected odor signals. The organic transistors may be interconnected to form a ring oscillator whose frequency of oscillation changes in response to an odor signal and in which the alternating signal applied to the gate electrodes of the organic transistors enhances their recovery and reduces their drift.

## Claims

### Claim 1

An analyte sensor comprising:
a series of N inverters, where N is an odd integer greater than 1, each inverter having a signal input terminal and a signal output terminal and including a first transistor with source, drain and gate electrodes, the gate electrode being connected to the signal input terminal of the corresponding inverter and the drain electrode being connected to the signal output terminal of the corresponding inverter;
wherein at least one of the first transistors is an organic transistor having a conduction path whose conductivity is responsive to presence of an odor with the signal output terminal of each inverter being connected to the signal input terminal of the next inverter in the series.

### Claim 2 (depends on 1)

The sensor of claim 1, wherein the signal output terminal of the last inverter of the series and the signal input terminal of the first inverter of the series are connected to form a ring oscillator.

### Claim 3 (depends on 2)

An analyte sensor as claimed in claim 2, wherein each one of said first transistors is an organic field effect transistor (OFET) having a conduction path whose conductivity changes in response to the selected odor incident on said first transistors.

### Claim 4 (depends on 3)

An odor sensor as claimed in claim 3, wherein the first transistors of every other inverter are of a first conductivity type and the first transistors of the remaining inverters are of a second conductivity type complementary to said first conductivity type.

### Claim 5 (depends on 2)

An analyte sensor as claimed in claim 2, wherein each one of said N inverters includes a second transistor; wherein one of said first and second transistors of each inverter is an odor sensitive organic transistor and the other one of said first and second transistors is odor insensitive.

### Claim 6 (depends on 2)

An analyte sensor as claimed in claim 2, wherein each one of said N inverters includes a second transistor; wherein one of said first and second transistors of each inverter is an odor sensitive organic field effect transistor (OFET) and the other one of said first and second transistors is odor insensitive field effect transistor (FET).

### Claim 7 (depends on 2)

An analyte sensor as claimed in claim 2, wherein each one of said N inverters includes a second transistor; wherein one of said first and second transistors of each inverter is an odor sensitive organic transistor and the other one of said first and second transistors is an odor insensitive organic transistor.

### Claim 8 (depends on 3)

An analyte sensor as claimed in claim 3, wherein each one of said odor sensitive organic transistor is a field effect transistor formed from one of the following materials:
(a) didodecyl α-sexithiophene (DDα6T);
(b) dioctadecyl (α-sexithiophene;
(c) copperphthallocyanine;
(d) α-sexithiophene;
(e) α,ω-dihexylsexithiophene;
(f) poly(3-alkythiophene);
(g) poly(3-hexylthiophene);
(h) poly(3-dodecylthiophene);
(i) hexadecafluorocopperphthallocyanine (F16CuPc); and
(j) naphthalenetetracarboxylic diimide compounds.

### Claim 9 (depends on 5)

The analyte sensor as claimed in claim 5, wherein each one of said first and second OFETs has a conductivity that decreases when the analyte OFET is subjected to the presence of the analyte.

### Claim 10 (depends on 2)

The sensor of claim 2, wherein the frequency of oscillation of the ring oscillator decreases when the ring oscillator is subjected to the analyte.

### Claim 11

A gas sensor comprising:
N inverters, where N is an odd integer greater than 1, wherein each one of said inverters has a signal input terminal and a signal output terminal; each inverter having a first transistor of first conductivity and a second transistor of a complementary conductivity type; the first and second transistors of each inverter being interconnected to form an inverter, one of the first and second transistors of one of the inverters being an organic transistor which is responsive to an analyte; and
the N inverters being connected in a cascade, with the signal output terminal of the last inverter of the cascade being connected to the signal input terminal of the first inverter of the cascade to form a ring oscillator.

### Claim 12 (depends on 11)

A gas sensor as claimed in claim 11, wherein said transistors are field effect transistors (FETs) and wherein each organic transistor is an organic field effect transistor (OFET).

### Claim 13 (depends on 11)

The sensor of claim 11, wherein the first and second transistors are organic field effect transistors with different sensitivities to the analyte.

### Claim 14 (depends on 11)

The sensor of claim 11, wherein the analyte is one of an odor, a chemical and a vapor.

### Claim 15 (depends on 13)

A gas sensor as claimed in claim 13, wherein the first transistors have active channels formed from one of the following materials:
a. didodecyl α-sexithiophene (DDα6T);
b. dioctadecyl α-sexithiophene
c. copperphthallocyanine;
d. α-sexithiophene;
e. α,ω-dihexylsexithiophene;
f. poly(3-alkythiophene);
g. poly(3-hexylthiophene); and
h. poly(3-dodecylthiophene);
and wherein the second transistors have active channels formed from one of the following materials:
hexadecafluorocopperphthallocyanine (F16CuPc); and
naphthalenetetracarboxylic diimide compounds.

### Claim 16

An apparatus comprising:
an odor-sensitive organic transistor having a semiconductor channel exposed to ambient odors; and
an odor-insensitive organic transistor having a semiconductor channel protected from ambient odors, the two transistors being interconnected together to generate an output signal dependent on currents flowing through the two transistors and on whether an ambient odor is present.

### Claim 17 (depends on 16)

An apparatus as claimed in claim 16 wherein the two transistors are of complementary conductivity type and are interconnected to form a complementary inverter.

### Claim 18 (depends on 17)

An apparatus as claimed in claim 17 wherein the output signal is generated by the inverter and the inverter has a switching point dependent on both transistors and on whether the odor is present.

### Claim 19 (depends on 16)

An apparatus as claimed in claim 16 further including a differential amplifier having first and second inputs coupled to the odor-sensitive and odor insensitive organic transistors, respectively, the output signal being a signal generated by the amplifier.

### Claim 20 (depends on 19)

An apparatus as claimed in claim 19, further comprising;
a feedback circuit to generate a feedback signal that stabilizes an output signal of the odor-sensitive organic transistor for drift with respect to an output signal of the odor insensitive transistor in response to a signal generated by the amplifier.

### Claim 21

A gas sensor comprising:
a ring oscillator including at least one organic field effect transistor (OFET), the ring oscillator having frequency of oscillation that is a function of whether at least one of selected odors is present; and
a circuit responsive to the frequency of oscillation of the ring oscillator and configured to provide an indication of when the oscillations of the oscillator are within or outside a predetermined range.

### Claim 22 (depends on 21)

The sensor of claim 21, wherein the oscillator is a cascaded chain of inverters, the inverters including odor-sensitive organic transistors.

### Claim 23

An odor sensing circuit including:
an organic field effect transistor (OFET) having source and drain electrodes defining the ends of a conduction path and a gate electrode; the conductivity of the conduction path of said OFET changing in response to selected odors incident on the OFET and in response to the value of voltages applied to the gate electrode;
circuitry for biasing the OFET so it is responsive to the application of odors; and
circuitry for applying an alternating signal to the gate of the OFET for enhancing its recovery to the condition existing prior to the application of any odors.

### Claim 24

An analyte sensor comprising:
first and second power terminals for the application of an operating potential therebetween;
first and second organic field effect transistors (OFETs) responsive to the presence of an analyte, each one of said OFETs having source, drain and gate electrodes;
the source and drain of the first OFET being connected between said first power terminal and a first node;
the gate electrode of the second OFET being connected to the first node; and
the source and drain of the second OFET being connected between a second node for producing thereat a signal indicative of the presence said analyte and one of said first and second power terminals.

### Claim 25 (depends on 24)

An analyte sensor as claimed in claim 24, wherein said first and second OFETs are of the same conductivity type and wherein the source of the second OFET is connected to said first power terminal.

### Claim 26 (depends on 25)

An analyte sensor as claimed in claim 25 wherein a bias voltage is applied to said first OFET.

### Claim 27 (depends on 26)

An analyte sensor as claimed in claim 26, wherein a third transistor is connected between said first node and the second power terminal, and wherein an output load is connected to the second node.

### Claim 28 (depends on 24)

An analyte sensor as claimed in claim 24, wherein said first and second OFETs are of complementary conductivity type and wherein the source of the second OFET is connected to said second power terminal.

### Claim 29 (depends on 28)

An analyte sensor as claimed in claim 28, wherein a bias voltage is applied to said first OFET; and wherein a third transistor is connected between said first node and said second power terminal and a fourth transistor is connected between the second node and the first power terminal.