d-Micro Geotechnical Crackmeter

YieldPoint’s d-micro is a high precision digital crackmeter with a 10mm range. It operates using an embedded microcontroller running the d-Tech firmware. It is most commonly used as a crackmeter in rock on the surface of concrete structures. d-micro has been used for applications such as:

  • monitoring any individual or interface crack in a structure
  • monitoring cracks in underground mines such as lunch rooms and garages
  • monitoring cracks in parking garages
  • monitoring cracks in dams under rehabilitation
  • monitoring cracks in residential structures subjected to blast vibration and fracing vibration
  • monitoring bridge-deck behaviour
  • monitoring of pillars and posts

The instrument outputs readings directly in degrees C and microns which eliminates the necessity for expensive analog-to-digital conversion. Readings can also be made using the USB port of a laptop or tablet computer (SensorViewer). Long term, low power, data logging is possible using the low cost dLoggers. A Real-time plug-and-play network of d-micro sensors or of any combinations of any other YieldPoint Instruments can be built in minutes using the IoT Gateway or d-Mesh. These features make solutions based on d-micro instruments significantly more cost effective than those of competing products. d-micro can be easily installed and removed from all types of structures using the convenient corrosion-proof nylon connectors.


The d-micro strain gauge is capable of 1 micron resolution over a range of 10mm. The gauge is attached to the structure using the #8-32 threaded rod at either end. The length of the sensor is 250mm and the diameter of the body is 7mm.

Signal Conditioning:

An on-board microcontroller provides temperature compensation, applies a 10-point calibration algorithm, and outputs an ASCII encoded RS485 (9600, 8, N, 1) signal.

Output Signal:

The output signal includes the instrument’s unique Sensor_ID, the Sensor_Type as well as the temperature and displacement data. The balanced differential RS485 output signal used is widely recognized for reliability in harsh environments. The signal can be routinely transmitted over 1,000m/3,000ft of lead-wire.

  • Individually calibrated for highest accuracy
  • High accuracy (0.5% FS) and resolution (0.01% FS =m 1 micron)
  • Digital (d-Tech) 10mm stroke length
  • Individual calibration with coefficients stored in memory.
  • RS485 Output signal (9600,8,N,1) ASCII encoded
  • Microcontroller provides output in real world units (mm and oC)
  • Unique ID facilitates plug-and- play networking
  • Digital temperature sensor for accurate compensation
  • Inductive, non-contact technology for immunity to hostile environments
  • Easy to interface with data loggers (d-Logger), Ethernet(IoT Gateway).
  • Competitively priced
Manual readout:

YieldPoint’s low cost d-Reader readout unit or the new d-TAB. Both provide the temperature and displacement data directly in oC and mm.

Data logging:

Data from the d-Exto can be collected using YieldPoint’s d-Logger dataloggers (d1Logger and d4Logger). Data can be download by any computer device running Windows including the convenient d-TAB.

Automated data retrieval:

Clusters of instruments (4 per Logger) that are monitored using YieldPoint’s d4Logger can be wireless networked using:

  • dMesh: a 900MHz wireless mesh solution.
  • IoT GateWay if Ethernet is available