How to Ruggedize/Waterproof Electronic Sensors for Long Life Operation: Analog Soil Moisture Sensors

Рет қаралды 14,872

5 жыл бұрын

This DIY video demonstrates a new technique for ruggedizing and waterproofing electronic sensors for long life operation in the field.
In this example we to take an off the shelf capacitive analog soil moisture sensor and further ruggedized and and waterproof the moisture sensor for long life operation.
The first step involves protecting the board with multiple coats of conformal PCB urethane seal coating. We then further seal the PCB using a dual-walled protective heat shrink that has also adhesive glue along the inner lining.
DIY Capacitive Analog Soil Moisture Sensor Kits (solder + heat gun required):
adosia.io/product/diy-waterpr...
Pre-built ruggedized sensors sold here:
adosia.io/product/rugged-anal...
For sealing and protecting electronics from the elements we use CRC Urethane Seal Coat Viscous Liquid Coating:
www.amazon.com/gp/product/B00...
Dual-Walled Glue Adhesive Lined Heat Shrink to cover sealed electronics:
www.amazon.com/gp/product/B01...
For bonding plastics we use 3M High Strength 90 Contact Spray Adhesive:
www.amazon.com/gp/product/B00...
Drip Irrigation 1/4" Tubing:
www.amazon.com/gp/product/B00...
Food Grade Crystal Clear Vinyl Tubing, 1/4-Inch ID x 3/8-Inch OD:
www.amazon.com/gp/product/B07...
Sign up for the Adosia IoT Platform: adosia.com
Adosia IoT Store - adosia.io

Пікірлер: 25

@s.kolodzie6007 Күн бұрын

Good idea with the shrink tubing! However, I can also recommend very brushable or sprayable liquid rubber instead of the clear varnish! The stuff with one or two coats over the upper electronics. I also painted the edges of the sensor board with liquid rubber ;)

@deaneatsgreens 5 жыл бұрын

Thanks for this! Found it super helpful, currently working with these exact sensors

@adosia 5 жыл бұрын

Awesome we're glad we could help. We actually have our first pass of our own spin in house and are hoping to be the lowest cost / highest performing capacitive moisture sensor solution.

@deaneatsgreens 5 жыл бұрын

@@adosia that's fantastic! I'll make sure to get one asap. Cheap and effective are the best combination

@flamesatdei 3 жыл бұрын

very cool

@jethrotull5847 2 жыл бұрын

Your very kind to share your knowledge when you also sell them pre weatherized on the web page. Your price is very fair but unfortunately they indicate “out of stock”. I’m in a hurry so I had to order the “ingredients” via Amazon.. again thanks for the recipe, I intend to do the same procedure to my D1 minis.

@jaisoh 5 жыл бұрын

Thanks for this. I would still seal the edges of the PCB also as unsealed FR4 can absorb the water (from the soil) and in the long run ruin the measurements and the sensor itself. For example epoxy glue or the spray you used would do the trick.

@adosia 5 жыл бұрын

Thanks for your thoughtful comments. We are running trials tests with sealing the entire board to see if that has any effect on overall performance . We see some cases where the soil medium may be coarse and more prone to scratch the solder mask off the PCB exposing the copper. We're also trying to determine if sealing the edges out will lengthen the intervals between requiring new calibration. Thanks again.

@adosia 4 жыл бұрын

Ok so we sealed the entire PBC with the urethane conformal coat in another test - it still works, but with a reduced analog operating range.

@caffeinatedinsanity2324 2 жыл бұрын

You might also want to protect the capacitive plates unless you're dead sure that they're weatherproof. I had a sensor (it was a white one) that had its solder mask peel off and exposed the copper plates, which is a definitely a problem. So I wouldn't hesitatr to cover them with a bit of lacquer on in the worst case, plasti-dip them. Your sensor reading will be altered in the process but if you can live with calibrating your sensors differently, that should be fine. PS: the 0-5V output of those sensors don't translate into an actual measure so I'm kinda moving away from them and thinking about making my own

@rrittenhouse 5 жыл бұрын

How long does it take until the contacts corrode? I've always wanted to try this but everyone says they go bad quickly.

@adosia 5 жыл бұрын

Non applicable here. These are capacitive sensors, so the lead traces are never exposed to the elements. The sensors do perform better when recalibrated regularly - say every couple weeks to every couple months or so.

@cloviscareca 5 жыл бұрын

Thank you very much. Just tell me, how did you prolonged the wire? Which kind of cable did you use? Thanks

@adosia 4 жыл бұрын

The easiest way to lengthen the wire is to cut the connector in half right in the middle - then solder the each end of the severed connector wires to a 3-wire 24AWG (or 22AWG) extension cable in between. You can even use 3-wire utility wire found in most local hardware stores. You will want to seal each solder area with the same marine / adhesive lined heat shrink.

@cloviscareca 4 жыл бұрын

@@adosia Thank you very much. One more question: Won't the water fall into the sensor through the Heak Shrink top (It seems that It's not fully hermetic sealed from the top)?

@adosia 4 жыл бұрын

@@cloviscareca - no it's sealed - the heat shrink needs to be adhesive (glue) lined, and pressed together firmly once heated up. The glue inside the heat shrink seals out the water from entering from either the top or bottom once it's been melted using a heat gun.

@cloviscareca 4 жыл бұрын

How about encapsulating the whole sensor inside a big heat shrink? Would it still works? This sensor works even inside a thin plastic bag. Would it work inside a heat shrink?

@adosia 4 жыл бұрын

Maybe - we've treated the entire sensor with urethane seal which significantly reduces the analog reading range - but it still works. We're not really a fan of using that much heat shrink though as the dual-walled shrink is expensive. We also have shielded moisture sensors now, which help tremendously with stabilizing readings over longer wire runs.

@TheMarshallFan 4 жыл бұрын

Good clip. How did you waterproof the edges of the PCB? Since you were covering the sensor surface while applying the polyurethane spray I'm guessing not with that. I was considering running a bead of 2 component epoxy along the edges to seal them off completely, but I'm not sure if that interferes with the capacitive sensor element...

@adosia 4 жыл бұрын

We typically don't treat the edges of the PCB. In these cases we've found the sensors do require recalibration over time, but eventually reach a saturation point where recalibration is required far less frequently. With that being said, we have conducted tests in treating the entire PCB (including edges) with multiple coats of the same urethane sealant used in the video. We found the analog capacitive sense range tightens when treating the entire sensor. For example, a sensor treated as in the video might exhibit an analog range of 250 (wet) to 750 (dry), whereas treating the entire sensor might yield a range of 525 (wet) to 750 (dry). With that being said, I don't think treating the edges alone as you suggested will affect the capacitive readings much if at all.

@TheMarshallFan 4 жыл бұрын

@@adosia Thank you for the detailed reply! I'll take your points into consideration and make an A/B comparison of the concepts and their respective performance. I forgot to point out that my sensors are the cheaper import version of this module, so the production quality likely is lower (I.e. the edge leaking might be more prominent)

@adosia 4 жыл бұрын

@@TheMarshallFan awesome. Let us know how it goes. We'd love your feedback. Happy holidays!

@TheMarshallFan 4 жыл бұрын

@@adosia So epoxying the edges didn't affect the sensor range at all and no water seems to be getting into the pcb as far as I can tell. So far so good! The only downside is the effort it takes to apply it evenly and without making a mess.

@Lenningx Жыл бұрын

@@TheMarshallFan I'm doing this right now, any updates on how it went?