Built-In Self-Test (BIST) Methods for MEMS: A Review

A novel taxonomy of built-in self-test (BIST) methods is presented for the testing of micro-electro-mechanical systems (MEMS). With MEMS testing representing 50% of the total costs of the end product, BIST solutions that are cost-effective, non-intrusive and able to operate non-intrusively during system operation are being actively sought after. After an extensive review of the various testing methods, a classification table is provided that benchmarks such methods according to four performance metrics: ease of implementation, usefulness, test duration and power consumption. The performance table provides also the domain of application of the method that includes field test, power-on test or assembly phase test. Although BIST methods are application dependent, the use of the inherent multi-modal sensing capability of most sensors offers interesting prospects for effective BIST, as well as built-in self-repair (BISR).

The Advantages of using 3D Printed MEMS Devices

The purpose of this study will be to discuss the potential benefits of 3D printed components when used in MEMS testing applications. The serving example for this study will be a critical component that is used in a transmissibility test of a mechanical isolator when subjected to a range of frequencies. The critical component is called a fixture. The fixture is the interface between the isolator and the shaker. The fixture is what allows the shaker to transmit mechanical vibrations to the isolator. It will also serve as a reference point for the laser vibrometer that will be a used in the test. Additional details as well as images of the testing environment will be included in the final paper. To illustrate the benefits of a printed component, it will be compared to a machined fabricated component. The machined fabricated component is block of milled Plexiglas that serves the same role. The machined fixture will serve as the control. Details on why machined fabricated components are used in the testing environment will be included in the report. The comparison will be based on how consistent the component will fix the isolator to the shaker. The response of the isolator when subjected to a range of frequencies is highly dependent on a number of factors. How well the fixture transfers the shaker's mechanical vibrations to the isolator is one of those factors. The test will begin with the machined fabricated component serving as the fixture. A sweep across a range of frequencies will be initiated and a sample of the isolator's response will be collected. This process will be repeated 500 times and averaged to make a set. Five sets of 500 samples will be collected. Once the five sets are collected, the test will pause and the isolator will be removed from the fixture and placed back into the fixture at a different orientation. In theory, both the isolator and the fixture have symmetrical geometry such that rotating the isolator should not affect the frequency response. Once the isolator is placed back into the fixture, five more sets will be collected. The test will collect five sets of test data from four isolator orientations. After performing the test with the machined fabricated fixture, an identical test will be executed using a printed fixture. After completing the test with both fixtures, the data will be presented and direct comparison between the fixtures can be made. Most data will be presented on a magnitude vs frequency graph. Explanation behind this type of graph will be included in the final paper. After presenting the collected data, other comparisons between fixtures will be discussed. Comparisons include the cost of manufacture, ease of use, and speed of design and development. Data will be included with these comparisons. Once all comparisons are discussed, final conclusions will be made. Final conclusions will state how printed components are better than machined components in this test and how additive manufacturing can become a critical asset in future MEMS testing and development.

A Review on Key Issues and Challenges in Devices Level MEMS Testing

The present review provides information relevant to issues and challenges in MEMS testing techniques that are implemented to analyze the microelectromechanical systems (MEMS) behavior for specific application and operating conditions. MEMS devices are more complex and extremely diverse due to the immersion of multidomains. Their failure modes are distinctive under different circumstances. Therefore, testing of these systems at device level as well as at mass production level, that is, parallel testing, is becoming very challenging as compared to the IC test, because MEMS respond to electrical, physical, chemical, and optical stimuli. Currently, test systems developed for MEMS devices have to be customized due to their nondeterministic behavior and complexity. The accurate measurement of test systems for MEMS is difficult to quantify in the production phase. The complexity of the device to be tested required maturity in the test technique which increases the cost of test development; this practice is directly imposed on the device cost. This factor causes a delay in time-to-market.