In 2018, sensors will continue to be a driving force for innovation. Low-cost sensors are revolutionizing medical, home health and wearable devices, as well as other Internet of things gadgets. These smart devices benefit from the ongoing development and fusion of low-cost, high-volume sensors.  Whether it is temperature, pressure, vibration, acceleration, flow, sound or vision, it is all about sensors. They are critical to the rapid innovation we see today.

Commonly overlooked aspects when designing with sensors

Calibration

Products that rely on one or more embedded sensor need not only testing but also sensor calibration to verify the accuracy and precision of measurements and ensure that different individual devices give the same result.

A sensor that nearly meets the accuracy requirements may only need a single-point calibration to remove the offset error. For many sensors, the largest error is the offset and a single-point calibration can significantly improve accuracy. A less accurate sensor or a more demanding application may need a two-point calibration to remove offset and gain errors. Calibration requires subjecting the sensor to two different levels of temperature, pressure, or whatever is being calibrated, usually near the extremes of the range. For a temperature sensor, there is a time delay in reaching a stable temperature, adding cost to the calibration. A sensor that is far from meeting the accuracy requirements or one that is very nonlinear may need to be calibrated at multiple points to compensate for offset, gain, and linearity errors.

Difference between precision and accuracy

It might sound tedious, but it is important when taking sensor measurements to understand the difference between precision and accuracy.

  • Accuracy = did I hit center of the target
  • Precision = how tight is my grouping
  • Repeatability = how does today compare to yesterday

Not understanding these requirements can lead to products with intermittent issues.  A device that is accurate but not repeatable may not always be accurate, for example.  Or a device that is precise but not accurate may never have an accurate enough reading.

Aliasing

Data acquisition is the sampling of continuous real-world information to generate data that can be manipulated by a computer. Acquired data can be displayed, analyzed, and stored on a computer. And it is important when capturing the measurement that you don’t create false artifacts.

Without going into the math, the Nyquist theorem states that the sample rate must be at least twice the highest frequency to measure all the frequencies present. In fact, if the sample rate is too slow you not only don’t measure the highest frequency, but lower frequencies are created in the data that didn’t exist in the input signal! Without care the sensor measurements may be just wrong.

We are sensor experts

Voler Systems provides electronic product development services. We develop products from concept to circuit design, circuit board layout, engineering prototypes, and transfer to production.

We can help

  • Design IoT and sensor based products
  • debug and fix intermittent issues
  • perform a design review of your sensor measurement

We are committed to delivering quality electronic products that are easy to manufacture. Voler Systems provides design, development, risk assessment, and verification of new devices for medical, consumer, and industrial applications. Voler is experienced in designing wearable and IoT devices, using its skill with sensors and wireless technology.

Contact us at info@volersystems.com or 408-412-9175