Fraunhofer ENAS developed different kinds of wake-up generators. The wake-up generators can be used to increase the service life of autonomous sensor systems, as during phases without external events, these run in the power down mode - the mode with the lowest energy consumption. If a mechanical event occurs externally, it is converted into an electrical signal that wakes the sensor system and ensures that the full amount of energy is supplied. One of the wake-up generators is demonstrated in a die. In power down mode, the overall system uses less than 1.35 μA – considerably less than previously available systems. This means that a long service life and highly precise measurements no longer have to be mutually exclusive. Whether for monitoring transported goods or the health of structural components, the new energy-saving systems can be used in many applications.

The institute shows also a power down interrupt generator (PDIG). The PDIG is a Fraunhofer ENAS patented smart solution energy and size limited applications with detection of mechanical events. The PDIG is a piezoelectric MEMS based on thin film aluminum nitride. If any mechanical event occurs, the PDIG generates electric energy by itself and “wake up” any electric circuit, e.g. inertial sensors. This wake up module with ASIC control requires less than 300 nA current consumption. In the result the life time of an independent battery based system increases significantly.

Fraunhofer ENAS also presents a new type of spintronic magnetic field sensor with two-dimensional vector resolution for contact-free measurement of distances, speeds, and angles. The magnetic field sensor‘s functionality is based on the physical giant magnetoresistance (GMR) effect. Technologies such as PVD and plasma etching processes are employed for fabrication. Thanks to those micro- and nanotechnologies used, it is possible to attain a very high signal-to-noise ratio, very short response times, a high degree of miniaturization, and a very low level of energy consumption. The GMR sensor is also bio-compatible. Conceivable applications range from the aerospace and the automobile industry to the very latest devices in medical engineering.

Fraunhofer ENAS in an active member of MEMUNITY, the industry driven community of MEMS test. At the of Polytec – booth number 330 – the MEMUNITY will present a wafer prober with a probe card developed by Fraunhofer ENAS. As further equipment development the MEMS Active Probe for Wafer and Chip Level Characterization of MEMS will be shown. The fabrication of MEMS with batch processing calls for a challenging characterization of the MEMS, especially in the case of a 100-percent testing. For the functional test of many of micromechanical structures it is necessary to measure the mechanical motion. A capacitance-change to voltage conversion is a cheap and commonly used method. To achieve an optimal signal to noise ratio, it is desired to have the conversion as close as possible to the MEMS. The presented “MEMS Active Probe” has been developed and built by Fraunhofer ENAS for exactly this case of application. It allows the measurement of the motion of micromechanical elements. The “MEMS Active Probe” covers the frequency range up to 200 kHz (3 dB) with a sensitivity of 90 mV/nA. The output impedance is matched to 50 Ohm to be directly used with a spectrum analyzer. The bracket can be used with common positioners. The MEMS Active Probe is applied for dynamic measurement of low currents (pA to nA).

In cooperation with SEMI, MEMUNITY organizes the 2014 MEMS Testing and Metrology Workshop at SEMICON Europa in Grenoble on October 7 and 8. The workshop is a platform to discuss needs, challenges, and trends in MEMS development, testing and metrology at a high level expert event.