App note: Thermal mass flow sensors for gas and liquid applications


White paper from Integrated Device Technology on the emergence of MEMS thermal mass flow sensors. Link here (PDF)

Flow meters represent the instrumentation of flow sensors and are used to measure the amount of flow that passes through them. There are in principal five different flow meter types: velocity flow, positive displacement flow, differential pressure flow, open channel flow, and mass flow. Mass flow meters are one of the dominant types in the market due to their faster response and better accuracy than other flow meters. They can also be effectively miniaturized and manufactured on silicon wafers. The emergence of MEMS has already revolutionized the consumer electronics market for motion, pressure, and other sensors, and similar micro-machining processes are now being adapted to fabricate flow sensors. Flow sensing applications are typically high-mix and low-to-medium volume compared, for example, to motion sensors that have become ubiquitous in hundreds of millions of smartphones. This paper will focus on the emergence of thermally-based MEMS mass flow sensors and how they match up with existing and more traditional flow sensor technologies.

Teardown of a Piezoelectric vibrating gyroscope


Kerry Wong did a teardown of an old analog piezoelectric vibrating gyroscope:

Gyroscopes nowadays are based on micro-electro-mechanical systems (MEMS) technology. They are low cost and extremely miniaturized. A device combing both a three-axis gyroscope and a three-axis accelerometers (sometimes these devices are referred to as 6DOF devices) such as the MPU-6500 for example can be had in a QFN package as small as 3 mm x 3 mm and under 1 mm in height. Before these MEMS devices gained mainstream popularity however, larger piezoelectric vibrating gyroscopes were used in many consumer electronics devices.

See the full post on his blog.

Check out the video after the break.

App note: An Introduction to MEMS Microphone Specifications


An application note from Cirrus Logic on their MEMS microphones, which are small and perfect for wearables devices. Link here (PDF)

MEMS microphones are small form factor microphones, which translate acoustic sound pressure input into an electrical output response. They utilise the silicon wafer processes from the microelectronic industry to create high performance microphones of increasingly smaller geometries.

These processes give MEMS microphones a number of advantages over conventional electret condensing microphones (ECM), which has resulted in a general market transition to MEMS technologies for many of the latest consumer applications, including those requiring multi-microphone support or high quality capture.

The aim of this applications note is to enlighten readers with little or no experience of MEMS microphones to a point that they are confident in basic terminology and able to understand datasheet information to make product selections.