Test challenges from emerging technologies

Cutting-edge fields, such as fuel cells and nanotechnology, hold much promise for improving our quality of life, says Joseph P. Keithley, but engineers must first fully understand these technologies—and their limitations.

T&MW: How are fuel cells challenging test engineers?

Keithley: We need to make improvements in costs and durability before fuel cells can become viable in such applications as cameras and laptop computers. Here, electrical test is an essential enabler. We need to perform tests that observe the different chemical reactions and associated losses that take place in a fuel cell. A fuel cell's polarization curve provides good insight into these issues. We obtain these curves by measuring the cell voltage drop as a function of the current load. Measuring the fuel cell's internal resistance is another frequently performed test. Researchers require special measurement techniques to achieve very precise timing between application of the source signal and reading the cell's response.

T&MW: What equipment does Keithley offer for testing fuel cells?

Keithley: For measurements of cell temperature, fluid flow, and pressure, we offer data-acquisition boards and digital multimeter/switch systems. To characterize electrochemical phenomena, our SourceMeter instruments provide tightly integrated source-measure functions with the precise timing needed to sort out different types of cell losses. Most of these applications are PC-based, so we supply various Windows-based software packages and instrument drivers to facilitate setup, control, and data analysis.

T&MW: Moving to nanotechnology, what are the principal measurement challenges associated with these ultra-miniature devices?

Keithley: One of the main issues is dealing with ultra-low signal levels. You need highly sensitive, high-resolution instruments, such as electrometers, picoammeters, and nanovoltmeters. Test engineers must also be careful to avoid error sources, such as cable leakages and contaminating effects. Another challenge is the wide range of behavior that these nanotech materials and components exhibit. They can go from being a supreme insulator to being highly conductive. Imagine the range of test signals the instrument needs to handle—from extremely low currents to several amps. Keithley has developed a specialized SourceMeter instrument—Model 6430— for such challenges. It can measure currents below femtoamps, as well as resistance from below an ohm to higher than 10,000 TΩ.

T&MW: How is Keithley handling the technical issues presented by advanced flat-panel technologies, such as organic electroluminescent (OEL) displays?

Keithley: OEL displays, targeted especially for such small area applications as cell phones, are still grappling with design issues, such as material lifetimes. A valuable tool in this research is our SourceMeter family of current and voltage sources. Other test issues with this technology include handling higher levels of capacitance and the need to characterize these active light-emitting devices under both DC and pulsed DC operation. Keithley has created turnkey and customized test systems to serve flat-panel research, since each manufacturer has proprietary processes.

T&MW: How does Keithley get involved in emerging technology projects?

Keithley: To a great extent, we follow our customers as they venture into ever more-demanding applications. We also participate in industry conferences involved in advanced technologies, and we maintain relationships with many corporate, government, and university research labs.

For Keithley white papers on the test considerations of these emerging technologies, visit www.tmworld.com/bench .