Simplify gas sensor characterization testing with a source measure meter (SMU)

overview

         A gas sensor is a device that can convert certain information of the gas, including concentration and type, into acoustic, electrical, optical or digital information that can be used by operators, instruments, computers, etc., and is usually installed in the detection head of the monitoring system In the monitoring system, it is used to collect air data on site. According to the gas sensing characteristics, gas sensors can be divided into semiconductor type, solid electrolyte type, electrochemical type, contact combustion type, optical type and thermal conductivity type.

Among them, the semiconductor gas sensor is a device that uses the mechanism of gas adsorption to change the conductivity of the semiconductor itself for detection. It has the characteristics of high sensitivity, fast response, good stability, and simple use. It is widely used in smart phones. Household, automotive electronics, consumer electronics, wearable devices, medical, industrial process, environmental monitoring and other industries.

According to different materials, the semiconductor gas sensor has a large resistance span, covering the range of Ω~GΩ. Sorting gas sensors of different materials requires an efficient detection scheme.

Gas sensor electrical performance test using source measure meter source (SMU) equipment

         I-V testing involves applying a voltage or current to a device under test (DUT) and testing its response to the stimulus. Depending on the device under test (DUT), signal levels can be quite low, requiring highly sensitive source and measurement instrumentation and test techniques that minimize external sources of error, and require fast test speed and high test reliability Make sure.

Usually, gas sensor I-V characteristic test needs several instruments to complete, such as digital meter, voltage source, current source, etc. However, a system consisting of several instruments needs to be programmed, synchronized, connected, measured and analyzed separately, which is complex, time-consuming and takes up too much test bench space. Moreover, the use of single-function test instruments and excitation sources also has complex mutual trigger operations, greater uncertainty and slower bus transmission speeds.

         One of the best tools for performing I-V characterization is a source measure meter (SMU). The Source measure Meter can be used as a stand-alone constant voltage or constant current source, voltmeter, ammeter, and ohmmeter, or as a precision electronic load. Its high-performance architecture also allows it to be used as a pulse generator, waveform generator, and automatic current-voltage (I-V) characterization system, supporting four-quadrant operation.

Precise Sourcemeasure Meter (SMU) Solutions

         Since 2015, Precise has been committed to the research of digital source measure meters, and took the lead in realizing the localization of digital source measure meters in 2019. It has successively launched products such as high-precision digital source measure meters and plug-in source measure meters. Through different technology combinations, it can Realize the diversification and optimization of product portfolio solutions, meet different customer needs from cost to performance, and help users easily solve various problems and needs encountered in gas sensor testing, such as:

(1) Real-time test the response sensitivity of the resistance value of various materials under the same gas condition;

(2) The resistance measurement of the lower and higher range spans (Ω, KΩ, MΩ, GΩ) is performed at low voltage, and the input resistance of the test equipment is required to be high

(3) I/V curve scanning;

(4) The upper computer displays the R/t curves of different gas-sensitive resistors in real time, and can record and archive them;

Solution 1: S series high-precision digital source measure meter + PC software to build a multi-channel test solution

         S100 digital source measure meter is the first domestically produced source measure unit with high precision and large dynamic range built by Precise for many years. It integrates the input, output and measurement functions of voltage and current. The voltage range is from 300uV~30V, the current is from 100pA~1A, the output accuracy reaches 0.1%, the maximum power can reach 30W, and it can cover the sensor measurement of the resistance value between 0~50GΩ.

Solution 2: CS1010C + CS100/CS400 plug-in source measure meter + PC software to build a multi-channel test solution

         This solution mainly adopts Pusys plug-in card equipment (CS1010 host + CS100 sub-card or CS1010 host + CS400 sub-card) to build a multi-channel test solution, which has the characteristics of high channel density, strong synchronous trigger function, and high efficiency of multi-device combination.

         CS1010C mainframe: adopts a custom framework, the bandwidth of the backplane bus is up to 3Gbps, supports 16 trigger buses, meets the needs of high-speed communication of multi-card devices, and has a slot that can accommodate up to 10 cards;

         CS100 sub-card: it is a single-card single-channel sub-card with four-quadrant working capability, a maximum voltage of 30V, a minimum current of 100pA, an output accuracy of 0.1%, and a maximum power of 30W; with the CS1010 host, a maximum of 10 test channels can be built to cover Sensor measurement of resistance value between 0~50GΩ;

         CS400 daughter card: It is a four-channel digital card with a single card, 4 channels in the card share the same ground, the maximum voltage is 10V, the minimum current is 10nA, the output accuracy reaches 0.1%, and the maximum power of a single channel is 2W; it can build up to 40 test channels with the CS1010 host computer. Sensor measurement capable of covering resistance values between 0 and 25MΩ;

Solution 3: CS1010 + A400 acquisition card + S100/CS100 + PC software to build a multi-channel test solution

         The solution is mainly composed of 1 CS1010 host, N A400 acquisition cards, 1 S100 or 1 CS100 sub-card. A400 collects the voltage value at both ends of the precision resistor (R1), and all test channels are connected in parallel to be powered by S100/CS100.

         A400 data acquisition card: a plug-in card independently designed and developed by PRECISE, a high-precision data acquisition card that supports variable rate sampling and large-capacity data storage; uses a high-performance ADC chip, with a resolution of up to 16bits and a maximum support of 2MS/s Sample rate, input impedance up to 1GΩ. A single acquisition card supports 4 channels, and the channels are isolated; with the CS1010 host, a maximum of 40 test channels can be built, and the test resistance range depends on the resistance value of the precision resistor.

Frequently Asked Questions

         (1) Is it necessary to use the 4-wire wiring method when testing?

Generally not necessary. The research and development of gas sensitive resistors is to identify the most sensitive material to gas and study its characteristics. The resistance value of the gas sensitive resistor is much larger than the wire resistance, so there is no need for four-wire wiring.

         (2) Can a multimeter be used to test gas sensitive resistors?

Multimeters are generally only suitable for static tests to determine resistance. For large-scale and dynamic research and development, digital source measure meters are the best choice. The high-precision source measure meter independently developed by Proceed has the advantages of large dynamic range and high input impedance, and can cover the test requirements of gas sensors in different resistance ranges from Ω to GΩ.

         (3) Compared with the resistance meter, what are the advantages of the source measure unit?

The common resistance meter has the advantage of high precision and high sensitivity, but its test principle is consistent with that of the source measure meter, which provides a constant current source to measure the voltage to convert the resistance value. The constant current source of the resistance meter has several fixed gears, which is not as flexible and convenient as the current of the constant current source of the Proces meter.

         (4) What are the characteristics of the multi-channel R/t test host software?

Support ≤40 channels to draw R/t characteristic curve synchronously and in real time; support constant current source or constant voltage source custom linear output mode switching; resistance value range dynamic and automatic change; with timing scanning and continuous test function; test frequency can be adjusted according to NPLC value ; Also has adjustable multi-point data smooth R/t curve switching; supports test data export; supports Ethernet, RS-232, GPIB fast connection communication and other characteristics.

in conclusion

         Qualification of sensors for gas detection systems and analytical instrumentation can be simplified by using I-V characterization techniques in the early stages of sensor research. Whether it is for new materials, new technology research and development, or sensor production testing, I-V characteristic analysis technology is used in various sensors and the selection of the best testing instruments. Proceed is a reliable partner for users. Welcome to contact us at any time.