The smartphone accelerometer myth
At first glance, it’s a fair question: why spend over $1,000 per measurement channel on a professional vibration monitoring system when a $2 sensor in your smartphone can seemingly do the same thing?
To demonstrate the difference, Dino Florjancic of MonoDAQ — DJB’s recommended distributor in Slovenia — compared a smartphone accelerometer with a professional-grade IEPE system comprising the DJB A/123 miniature piezoelectric accelerometer and the MonoDAQ-1xACC data acquisition device.
The setup: pro-grade vs. smartphone-grade
The Google Pixel smartphone uses the Bosch BMI160 MEMS sensor — a tiny integrated chip (2.5mm x 3mm) featuring a triaxial accelerometer and gyroscope. It handles everyday phone tasks: motion detection, orientation, and gesture response.
In contrast, the DJB A/123 accelerometer and MonoDAQ hardware form a high-end system built for precision vibration testing, including automotive, aerospace, and industrial applications. It offers:
- Up to 40,000 samples per second
- A bandwidth up to 2 kHz
- Dynamic range up to ±500 g
Compare that to the smartphone sensor’s 400 samples per second and a range limited to ±16 g, and the performance gap becomes clear.
Real-world testing: driving, bumps, and drops
To compare performance, the smartphone and the IEPE sensor were mounted together in a car. Data was collected simultaneously during idling, urban driving, highway speeds, and while hitting bumps.
Summary of results
- Idling: 0.4 g RMS
- City driving: 0.8 g RMS
- Highway: 0.13 g RMS
In low-frequency conditions like driving, the phone performed surprisingly well — its data correlated within 15% of the professional system. But that changed dramatically under dynamic conditions.
Spot the difference: hitting a bump
When hitting a road bump:
- Phone sensor: Recorded a peak of ~2 g
- IEPE sensor: Captured a true peak of -4 g
The smartphone’s limited bandwidth and resolution failed to capture the full range of vibration, highlighting its limitations for any kind of meaningful analysis.
Extreme testing: dropping the phone
To push the sensors further, the phone was dropped from a few centimetres onto a table. The professional sensor recorded a peak shock of 87 g, well beyond the phone’s ±16 g capacity. The phone simply couldn’t resolve the impact accurately.
So, what’s the verdict?
MEMS sensors like those in smartphones are great for general movement detection, gaming, and basic monitoring. But for applications involving:
- High precision
- High-frequency vibration
- Accurate peak detection
- Data reliability
...only professional-grade accelerometers and acquisition systems like those from DJB and MonoDAQ are up to the task.