GAS SENSOR WITH HEATER
A breath analyzer detects a breath component in a breath sample. The analyzer includes a sensor for sensing the breath component and a temperature control system integrally formed with the sensor. The temperature control comprises a resistive temperature device configured to heat the sensor to a predetermined temperature. The resistive temperature device also senses the temperature of the sensor. A controller is operatively connected to the sensor to receive breath component information sensed by the sensor.
1 . A breath analyzer for detecting a breath component in a breath sample, the analyzer comprising:
(1) a sensor for sensing the breath component;
(2) a temperature control system integrally formed with the sensor, the temperature control comprising a resistive temperature device configured to heat the sensor to a predetermined temperature and to sense the temperature of the sensor; and
(3) a controller operatively connected to the sensor to receive breath component information sensed by the sensor.
2 . The breath analyzer of claim 1 , wherein the sensor comprises a metal oxide deposited on a substrate.
3 . The breath analyzer of claim 2 , wherein the metal oxide comprises tungsten trioxide.
4 . The breath analyzer of claim 2 , wherein the substrate comprises aluminum oxide.
5 . The breath analyzer of claim 2 , wherein the temperature control system comprises a platinum metallization deposited on the substrate.
6 . The breath analyzer of claim 5 , wherein the metal oxide is deposited on a first side of the substrate and the platinum metallization is deposited on a second side of the substrate.
7 . The breath analyzer of claim 1 , wherein the temperature control system comprises a closed-loop control circuit selectively controlling the resistive temperature device.
8 . The breath analyzer of claim 7 , wherein the control circuit comprises a bridge circuit operably connected to an operational amplifier.
9 . The breath analyzer of claim 8 , wherein the bridge circuit comprises four resistors; the resistive temperature device acting as one of the resistors.
10 . The breath analyzer of claim 7 , wherein the control circuit comprises a processor controlling a resistive divider, resistive divider comprising the resistive temperature device connected in series with a shunt resistor.
11 . The breath analyzer of claim 10 , wherein the processor controls the voltage provided to the resistive divider according to a voltage drop across the resistive divider.
12 . A breath analyzer for detecting a breath component in a breath sample, the analyzer comprising:
(1) a metal oxide sensor for sensing the breath component;
(2) a temperature control system integrally formed with the sensor, the temperature control comprising a metal resistor having a positive temperature coefficient, the metal resistor being configured to heat the sensor to a predetermined temperature and to sense the temperature of the sensor; and
(3) a controller operatively connected to the sensor to receive breath component information sensed by the sensor.
13 . The breath analyzer of claim 12 , wherein the temperature control system comprises a closed-loop control circuit selectively controlling the metal resistor; the metal resistor being integrally formed with the closed-loop control circuit.
14 . The breath analyzer of claim 13 , wherein the control circuit comprises a bridge circuit operably connected to an operational amplifier.
15 . The breath analyzer of claim 14 , wherein the bridge circuit comprises four resistors; the metal resistor acting as one of the resistors.
16 . The breath analyzer of claim 13 , wherein the control circuit comprises a processor controlling a resistive divider, resistive divider comprising the metal resistor connected in series with a shunt resistor.
17 . The breath analyzer of claim 16 , wherein the processor controls the voltage provided to the resistive divider according to a voltage drop across the resistive divider.