SGAS701 Datasheet

© 2017 Integrated Device Technology, Inc.

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November 16, 2017

Table 3.

Temperature Specifications

Symbol

Parameter

Conditions

Minimum

Typical

Maximum

Units

Sensor Operation Temperature

240

°C

Recommended Environmental

Temperature Range

-20

50

°C

Maximum Storage Temperature Range

-50

125

°C

The sensor is not intended for continuous operation above or below the environmental temperature specification, but exposure for short

durations will not will not harm the sensor.

4. Sensor Characteristics

IDT’s solid-state chemiresistive sensors are an advanced type of gas-sensitive resistor; i.e. they sense the presence of a target gas through a

change in resistance of the sensing element. Most sensors exhibit reduced resistance as gas concentration increases, typically over several

orders of magnitude across the sensing range.

Solid-state chemiresistive sensors show a reduced resistance with increasing gas concentration according to Equation 1:

-α

Equation 1

specific sensors or sensing materials, the fundamental resistance versus concentration relationship for all of IDT’s n-type sensors follows

Equation 1. Taking the log of both sides of the equation results in Equation 2:

Equation 2

This shows that log resistance versus log concentration is linear.

An immediately observable consequence of Equation 1 is that sensor resistance will change rapidly at low concentrations and much less at

high concentrations. This is illustrated in the following example:

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The non-logarithmic response plot shown in Figure 3 illustrates the fundamental challenge that must be addressed when measuring the

resistance of chemiresistor sensors and relating these measurements to gas concentrations. Additional nonlinear effects from the measurement

circuitry exacerbate these challenges and must be understood in order to account for or eliminate these effects.