MEMS Sensors Key Technology for the Internet of Things

BoschMEMsMEMS sensors can measure a range of variables. In early 2014, Bosch Sensortec unveiled a world exclusive in sensor technology – the BME280 integrated unit, which combines sensors for pressure, humidity and temperature in a single housing. The unit was specially developed for applications related to environmental monitoring, indoor navigation, smart homes, personalized weather stations and sports and fitness. Within a second, it can determine humidity. It also offers precise measurement of ambient temperature and low energy consumption. In addition, Bosch is making its sensors increasingly smart. Production is about to begin on the first sensor for measuring physical variables, such as acceleration, rotary motion, and the earth’s magnetic field, and it will also include a micro-controller for evaluating readings.

The introduction of MEMS sensors in automotive electronics in the 1980′s and 1990′s marked the first wave of their surging popularity. The second major wave has been their widespread use in smart phones since the beginning of the 21st century, and the internet of things now heralds the third wave. Sensors, signal processing, batteries, and transmitters have become so small, energy efficient and economical that they can be used in their billions. At the same time, radio networks are available almost everywhere. This makes MEMS the key technology for connecting things over the internet. MEMS must be equipped with a radio chip and a battery, and they must possess software intelligence, because only relevant data should be transmitted to the internet, not raw data. This local data processing calls for the special kind of systems expertise that Bosch brings to the table. In 2013, Bosch launched a door sensor that reports suspicious movements to the home owner’s smart phone. In the future, windows will control the heating or alarm system via unobtrusive sensors, and bracelets with embedded sensors will call for help if their wearer suffers a fall. Web-enabled sensor technology will be in everything that is “smart,” not just in smart phones.

A key aspect of Bosch’s future sales growth is web-enabled products and web-based services. The company considers itself well-positioned for such growth thanks to its hardware know-how and broad technological expertise. To unlock this business area, Bosch founded Bosch Connected Devices and Solutions GmbH at the end of 2013. It supplies compact electronic products and software expertise designed to make devices intelligent and web-enabled across a broad range of applications. The focus is on the development of connected sensors and actuators. Actuators convert electrical signals from sensors and control units into a physical action, such as automatically switching a light on and off or opening and closing a valve. Initially, business activities are concentrating on sensor-based applications for intelligently networked homes, or “smart homes,” as well as activities in the fields of traffic, transportation, and logistics – because in the future, consignments of critical goods will be able to transmit data on any unusual status changes directly to logistics centers.

MEMS sensors contain the finest silicon structures. As the casing moves, these structures shift a fraction of a thousandth of a millimeter – and their electrical properties change in the process. These properties can be measured and converted into a data stream. The dimensions are incredibly small; while a human hair has a diameter of 70 thousandths of a millimeter (70 micrometers), some components measure only four micrometers – that is 17 times smaller than the diameter of a single human hair. Since the micromechanical sensor produces only weak electrical signals, the developers built in another electronic component – sometimes in the casing beside the sensor, sometimes even directly on the same chip. This second component processes, amplifies, and converts the weak signal into digital data. In this way, MEMS (micro-electro-mechanical systems) sensors can supply control units directly with readings.

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