Sensor Node Packaging

This page describes ideas and notes for packaging of the sensor node.

Summary List of Next Steps

  1. Create some kind of interface for a set of plastic layers to fit around a grease bearing.
  2. Design the PCB to fit around this interface. These will need to be layered up.
    1. This could be a donut shape for grease to go through (donut-shaped)
    2. This could also use angled fitting to go through our sensor as well, in which case it would not be symmetrical - have a port on the side.
  3. The housing could only be designed after the shape of the PCB is known.
  4. The elements that require access to the surface (eg: hygrometer, status LEDs) must have proper access and possibly also small gaskets to seal the inside of the sensor from dust and humidity.
  5. The microphone will also require access to the surface, however a thin protective layer can be applied to the input of the microphone to seal it from dust and humidity.
  6. The assembly screw size should be as uniform as possible in this design.

Criteria for thinking about designs:

  • Could I separate insulated components (processor, microphone) from coupled components (thermometer, accelerometers)?
  • Could I squeeze the ambient environment sensors (microphone, hydrometer) next to port openings (with gaskets) to ensure that they have access to the environment?
  • Could I easily attach the metal screw to the plastic housing?
  • Could I connect the PCBs together in a way that will still let someone crack it open without damaging it?
  • Could the batteries be replaced easily without taking out a ton of componnents?
  • Could I picture my dad taking it apart and putting it back together?
  • Could I use the same screw size over and over?
  • Could I expand this in the future?
  • Will the antenna work through the housing?

Notes from Meeting with Client

The goal of this project is to create a product that could interface with industrial, rotation equipment and collect data.
  • It would be great to mount this sensor in the grease fitting - that way it would be embedded in the monitored device (more accurate temperature and vibration data) and we wouldn't need to alter it with extra hardware. Although it might take the grease fitting out of commission. Unless we used a pass-through for the grease.
  • Fittings:
    • Any bearing failure is a grease failure
    • ¼"-28 – ½" hex nut, ball check valve – for grease to go through – could go under the nut of the hex.
    • Heating up – give a shot of grease- should cool down
    • Could be a temperature interrupt?
    • Grease fittings way easier than epoxy
    • Pillowblock bearings with grease fittings are the most common thing we'll work with
    • Most problems from bearings – vibration
  • Typical grease bearing sizes: (note - you can also get an adapter between the two)
Under 2" - ¼-28
Over 2" - 1/8 -27 PTF
  • About pillow block bearings:
    • Stainless steel bearing, iron housing
    • Could actually use a speed sensing mechanism then - go through to the bearing rotor

Other Client Notes (Lower Relevance to Project)

  • RE: hardware specs
    • Don't want to get too attached to hardware for this tech - The top tech will change every 5 minutes (lightly paraphrased)
    • Sending all the data to Dumond labs or whatever – get access to data
    • Want to send everyone free sensors
  • Palantir, IBM partnering together (some info I found later:
    • Pitching idea of open-source, academic – for machine health (try and get it for free)
  • Mounting:
    • Could have a T fitting – could have a 90deg fitting for the grease
    • Put a gimble in the sensor, know the orientation – mathematically figure it out (re: axis of accelerometer)
  • Belleville spring washer
    • Disk-shape – would be nice to harvest energy from the spring energy, but the electronics under the arms of the spring
  • More on fittings:
    • There isn't an automatic grease management solution on the market for under $300 – "That would be a game changer"
    • Companies that use bearings that don't have grease fittings – more sophisticated tech, more sophisticated customers
    • Sidenote - these are grease fitting caps, which everyone should use, but no one has ever used in the history of the world 

Original Ideas Presented for Packaging

These ideas were presented before speaking with the client, so they do not incorporate a way of accessing the grease fitting from outside the sensor.

  • Sensor housing will include an easy way to access replaceable batteries.
  • Gaskets will be used to ensure dust and humidity will not get into the electronics.
  • A standard-sized screw mount (with an optional magnetic attachment) will attach to equipment.
  • Compartmentalization ensures serves components that need to be as close as possible to machine (ex: vibration, temperature) and components that need to be as insulated as possible from machine (ex: microphone, processor)
design_batch1.png design_batch2.png design_batch3.jpeg


  • Hinged puck style, with thin flex connectors between the different board layers. All surface-facing components would be mounted at the top. Closeness to the machine is preferred over thinness.


  • Preferred design of the three of them
  • Might be the most limited in space if we expand the size of the base.
  • Concerns about battery p


  • Use an L-shaped mounting bracket as a simple way to mount components.
  • Concentrate the space vertically instead of horizontally (based on ABB sensor).
  • Allows space for bigger batteries.


  • No obvious how to attach plastic housing to the base.


  • Industrial bulkhead connector for additional components (could be changed later).
  • the bottom would only have the processor, accelerometer, and the temperature sensor, and then the option top part could include acoustic and hydrometer, or whatever else someone in the future wants to add on.
  • Inspired by this design: (link)


  • Could require more work to get a modular interface.

See Also

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