Connect the Dots: Making Small Sense of the Environment

Create: 10/02/2017 - 20:24

While many participants in IoT are preoccupied with which wireless interface to use or how to gather and analyze data, Bosch-Sensortec has been busy applying its vast expertise in sensor design and integration to develop miniature, multi-function sensors. These small sensors get accurate, reliable, stable and consistent data under the most extreme circumstances.

For example, it’s surprising to note that a barometer can get more accurate location readings than a GPS system. That same barometer can be part of a tiny, low-power integrated sensor package that also measures temperature, relative humidity and ambient levels of volatile organic compounds (VOCs). These VOCs include those that are emitted from paints, lacquers, paint strippers, cleaning supplies, furnishings, office equipment, glues, adhesives and alcohol.

Bosch-Sensortec has integrated this level of capabilities into the BME680, an environmental sensor with a footprint of 3 x 3 mm and a height of 0.95 mm. Just for perspective, designers used to depend on delicate mercury-based barometers housed in boxes with dimensions measured in inches. Now a whole low-cost, low-power environmental lab can be put on a module 8.55 mm3 (Figure 1).

Bosch-Sensortec BME680 sensor

Figure 1: The integration of multiple sensing technologies into a low-power, low-cost module raises interesting questions about what’s possible for IoT solution providers. (Image source: Bosch-Sensortec).

For IoT solutions providers, BME680 inverts the question of what can the sensor do, to what can be done with the sensor? The types of applications range from wearables to emergency services, smartphones to smart cities and industrial IoT.

GPS vs. Pressure Monitoring for Accurate Location Tracking

Going back to location tracking, emergency services and in-building tracking of assets can make use of the fact that it’s often more accurate to use pressure sensing instead of GPS to track location. This seems counterintuitive, but in a building where the fireman or asset may be going up and down stairs and in and out of doors and crosswalks, the air pressure can be a very accurate indicator of location (Figure 2).

Bosch-Sensortec BME680 sensor

Figure 2: For emergency services and simple asset tracking in buildings, a pressure monitor can be more accurate than GPS, assuming the terrain is already mapped in a database. (Image source: Bosch-Sensortec)

Also, a GPS can be rendered ineffective due to building walls, especially deep within the inner rooms and basements. Even outdoors, buildings and trees can hinder a GPS system.

Much of this depends upon the accuracy of the sensor, of course. In the case of the BME680, it’s accurate to within 1.7 cm. Assuming the terrain is mapped carefully and stored in a database for quick reference, the location can be more accurately determined using pressure than GPS.

In reality, however, pressure and GPS would likely be used together, especially in emergency services applications.

The performance characteristics of the BME680’s other three sensors are just as impressive:

  • the gas sensor has a response time of under 1 second (for a brand new sensor)
  • the humidity sensor has an accuracy tolerance of +/- 3% (relative humidity)
  • the temperature sensor is accurate to +/- 0.5˚C

The BME680’s average current consumption, a critical factor for applications in wearables and remote monitoring applications, ranges from 2.1 microamps when measuring humidity and pressure, to 3.7 microamps when all four sensing functions are enabled. It requires voltages of between 1.71 to 3.6 V, and it connects to a controller using the common I2C two-wire interface.

The flexibility of the BME680 opens the discussion of what can an IoT solution provider do now that four critical sensors can be combined into one small device. The answer lies in the creative use of all four together, as well as using the sensor to augment other functions such as GPS, vibration, acceleration and rotation. This brings up the topic of sensor fusion, which together with reliable communications, will help chart the course for the next round of IoT innovation and solutions.

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Patrick Mannion
Patrick Mannion is an independent writer and content consultant who has been working in, studying, and writing about engineering and technology for over 25 years.

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