Project lead: Mitch Nelke nelkem@oregonstate.edu

Smart Rock

OVERVIEW

Hydrological models could greatly benefit from a low-cost method of acquiring continuous pressure and temperature data of small or intermittent streams. This is especially true in locations where conventional data collection mechanisms and resources to set them up are lacking. The Smart Rock is a submersible sensor suite that could fill that gap. The device's electronics consist of a Bluetooth-capable microcontroller, 4GB of SD card storage, a 1200mAH LiPo battery, a 7V solar cell and battery charger, and a pressure and temperature sensor. Everything is secured inside a waterproof PVC and acrylic case. Pressure readings have a resolution of 20 Pa and temperature readings have a resolution of less than 0.01 degrees Celsius. The Smart Rock has indefinite battery life when the average daily solar radiation is greater than 50 W/m^2. A phone held over the water can communicate with the device using Bluetooth Low Energy when it is submerged up to 20 cm in water, allowing users to collect data whenever it is convenient without having to remove the Smart Rock from the stream. The device's total material cost is less than $150 and has potential to be much lower. The Smart Rock's target use is for citizen science applications where the user can purchase or be given the device with instructions and then deploy it in a local stream. Whenever the stream is visited, data can be transferred to a phone and uploaded to a provided server.

The project is currently focused on providing a deployable sensor suite for CrowdWater, a citizen science project that provides opportunities for non-researchers to collect data on the quality of streams.

Objectives

  • To collect 10-minute data on stream temperature and pressure over the course of 6 months
  • To design a low-cost and easily replicated device that achieves the above.
  • The device should be simple to use and deploy so that it can be used for citizen science projects such as CrowdWater.
 

OUTCOMES

SR_demo.jpg

A demonstrative proof of concept was created in March 2018. It was not waterproof, but included a battery, microcontroller and pressure sensor. The device could communicate with a user's phone and send information such as battery voltage, air pressure, and air temperature. The first iteration of the Smart Rock is centered on this core functionality but includes SD storage for data, a solar cell and charger, and a waterproof shell.

FUTURE

Five Smart Rocks have been assembled and brought to Zürich, Switzerland to be deployed in the field. The pressure sensors are meant to be soldered with a reflow-oven with a specific temperature profile and also have lead-free solder on their pads. It is extremely difficult to hand-solder with their recommended PCB footprint and so attempting to do so can overheat and then permanently damage them. A new PCB footprint with longer, thinner pads could work, but a reflow oven might be necessary. 

Getting ready to assemble five Smart Rocks.

 First iteration of the electronics. 

First iteration of the electronics. 

KEYWORDS

SmartRock, Smart Rock, Feather M0, Arduino, Stream, Pressure, Temperature


REFERENCES

  • Websites
    • https://crowdwater.ch/en/welcome-to-crowdwater/
  • Software
    • Fusion360. (2018). San Rafael, California: Autodesk.
    • EAGLE CAD. (2018). San Rafael, California: Autodesk.