HX-711 Non-Operational Temperature

Components & Accessories
1

Hello,

I am a mechanical engineering student working on my capstone design project. I am reaching out regarding the Sparkfun HX-711 Load Cell Amplifier. We are prototyping a device with this unit, and our client would like to use an autoclave for sterilization with temperature ranges of 121-250 degrees C. From the technical document sheet I was able to find, it says the operational temperature ranges from -40 to 85 degrees C. My question is if the unit is not in operation during sterilization, would damage most likely occur to the unit in these autoclave temperature ranges, and if so which failures to the unit would most likely occur?

Thanks!

2

Frequent exposure of any electronic equipment to large changes in temperature will lead to damage from expansion/contraction of dissimilar materials.

Likewise, condensation of moisture due temperature changes will lead to chemical etching and development of conductive paths that destroy PCBs.

For reliability, obey the manufacturer’s operating and storage temperature range conditions as set forth in data sheets of each of the components.

How do a “capstone project” and a client fit together?

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3

Hi Jremington,

Thank you for your reply!

If I am understanding correctly, the primary concern is cyclic temperature exposure and its long term effects on reliability? While the board itself may be able to withstand a single exposure above the specified operating temperature range, repeated thermal cycling could introduce failure mechanisms over time?

Our university capstone projects are sponsored by external partners (stakeholders/clients) who define the project requirements and deliverables. Based on my current research, this particular requirement may be challenging to achieve reliably, so I wanted to seek professional perspectives before concluding whether this deliverable is feasible or if alternative approaches to sterilization should be pursued.

4

You’ll be hard pressed to find a general purpose PCB of any kind that can reliably withstand an autoclave, even one considered tougher than normal like an automotive keyfob or a very simple one like a smoke detector.

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5

Thanks Brow, I appreciate your input!

6

That is one of two primary concerns. The other is whether the components themselves are rated to withstand the highest temperature. Do your research and check the component data sheets, including the strain gauges and the methods/materials by which they are mounted.

IMO it is completely unreasonable to demand that the electronics be repeatedly sterilized in an autoclave. Ask the sponsor to explain this requirement.

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7

I came across this load cell today and noticed it has the highest temperature rating I’ve ever seen on this type of sensor: 150°C. Most top out at half that or perhaps 100 but they’re all well short of what can be expected in an autoclave.

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