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From Bob Helsel, Editor of the PXI Newsletter:

Welcome to the May 2018 edition of the PXI Newsletter.  Our intent is to educate and inform you about how the PXI standard is being used in modular test systems for a wide variety of industries.

In the New PXI Products section, we are showcasing PXI products recently released by members of the PXI Systems Alliance.

Our thanks go to PXI Systems Alliance, the sponsor of this month's issue.

Visit for more information.


Metal Oxide (MOX) Gas Sensor Testing

Submitted by Marvin Test Solutions

The application of MEMS technology has allowed Metal Oxide (MOX) Gas Sensors to be mass-produced at the wafer level with silicon wafer manufacturing offering cost reduction and scalability to large volumes. These gas sensor devices are suitable for precise measurement of Carbon Monoxide (CO) and a wide range of Volatile Organic Compounds (VOCs) such as Ethanol, Acetone and Toluene. Applications for these sensors, which are largely driven by health and safety considerations, include environmental monitoring, biological research, industrial control, portable breathalyzers and home air monitoring systems.

The adoption of MEMS technology for MOX gas sensors has resulted in greatly reduced manufacturing costs. However, each of these sensors must also be tested, which presents a unique set of challenges when compared to the manufacturing and testing of typical semiconductor devices. This white paper discusses how a semiconductor manufacturer of Gas Sensors employed a focused test solution that provided the required accuracy, accommodated very large site counts, and matched the over-all throughput performance of high performance semiconductor test systems at a much lower cost.

What is a MOX Gas Sensor?

The MOX Gas Sensor is a MEMS device (Micro- Electro-Mechanical System) fabricated as a multi-chip module (MCM). The basic components of the MCM are the micro-controller ASIC, pre-tested on the wafer, and the sensor, the object  of this test application. These components are placed on a common substrate and a lid is placed over the components with a small hole or mesh in the lid that allows gas into the sensor.

The sensor consists of a small heating element housed beneath a thin membrane coated with   a proprietary metal-oxide material. The MOX material is  a  variable  resistor  that  responds  to chemicals in the gas it is exposed to. The MOX can be formulated to respond differently   to certain types or classes of gas, called the target gas. In an environment  of  “clean”  air,  the MOX resistance can be several MOhms. When heated, and in the presence of the target gas, the resistance of the MOX material drops significantly, down to several tens of KOhms. When the application of heat is removed, and/ or the test gas is eliminated, the MOX resistance returns to its previous value.

With the application of controlled heat, measuring the resistance of the MOX coating in the presence of clean air, and then measuring the resistance of the MOX coating in the presence  of air with a controlled amount of the target gas (measured in Parts per Million), the ratio of the two measurements can be used to calibrate the device. In actual operation, the calibrated MOX resistance measurement is indicative of the density of the target gas in the environment.



Thanks to all our readers.
Bob Helsel, Editor

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New PXI Products

The PXI platform continues its explosive growth with many new product introductions. New products introduced in the last three months include (listed in the order received):

Marvin Test Solutions 4-Channel PXI Source Measure Unit
The GX3104’s unique flex-power architecture offers users the option to configure the SMU as a 4-channel, 250 mA/ channel SMU or as a single channel, 1A SMU – providing test engineers the flexibility to support both high current or multi-channel SMU applications with one module. 

Keysight PXI Avionics Databus Modules
Avionics interface modules from Avionics Interface Technologies, offered through Keysight, enable connectivity between your PXI test systems solution to DUT’s with aviation industry standard buses. These modules are capable of simulation, monitoring, record and play back of bus traffic enabling test and verification of avionics equipment data communication capabilities.

Teledyne SP Devices 14-bit Arbitrary Waveform Generator with 2 GS/s Sample Rate
The SDR14TX AWG offers a complement to the previously released ADQ14 and ADQ7 digitizer families and can be used either for stand-alone operation or in system-level solutions with well-matched signal generation and data acquisition performance.

Advanced Testing Technologies PXI/PXIe Inserts
The Advanced Testing Technologies PXI Insert allows the user to easily incorporate PXI/PXIe instruments into an existing VXI chassis.

NI PXIe-1095 Chassis with 58 W Power and Cooling per Slot

The PXIe-1095 chassis offers 58 W of power and cooling in every slot, 50 percent higher than all previous NI PXI Express chassis.


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