Custom Instruments – Integrating Sensor Modules

Posted on August 10, 2023

Christian-Veenstra headshot

Coanda’s instrumentation team is dedicated to getting the most out of our physical modeling experiments. Usually this means spec’ing and installing standard industrial instrumentation, and it can also mean designing and building instrumentation from scratch.

There’s a middle-ground too: component-level sensors and transducers that need to be incorporated into a larger assembly.

Such sensors often need to be soldered to a printed circuit board which provides a power supply and interprets the signal, either through analog circuitry or digitally via a board-level protocol like SPI or I2C. While it’s obviously more work than turnkey instruments, such components can have several advantages:

  • Fundamental measurement principles (hopefully!) all figured out, although often without extras like temperature compensation.
  • Bare-bones measurement usually means we have more control over temporal filtering: often there may be none at all, and the response time is limited by the fundamental measurement principle.
  • Since you are designing the PCB and enclosure, you have control over the final form factor. This might let you fit the measurement into areas that would otherwise be inaccessible.
  • Per-unit cost of such sensors is generally much lower than a comparable turnkey instrument. If only installing a few, it’s not worth the design time to use one, but if there is an array of a hundred the difference between a $30 component and a $300 (or $3000) instrument can be significant.
  • Similar to the above – the per-unit cost of getting the measurement into our data-acquisition system can also decrease for large numbers of sensors. An array of 4-20 mA industrial sensors also requires a lot of wiring, filter circuits, and digital-analog conversion channels. But, since we maintain our own in-house data acquisition software, we can incorporate a remote network of microcontrollers or embedded single-board computers instead.

Pictured is an array of dive/altimeter-watch modules mounted in a probe that can be plunged into depositions to measure pressure as a function of depth during consolidation.

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