Stiffening of thermistors

ebeowulf17

Joined Aug 12, 2014
3,282
I think for a medical scenario where you have cleaning and sanitizing requirements, trying to make your own probe is crazy.

I've not personally seen probes like you're looking for with thermisters, but options abound in thermocouples. I think you can do better and cheaper if you really shop around, but as a starting point, Omega offers 1.5mm thermocouple probes with handles starting around $45 each. Sealed, rigid, sanitary, reliable, done.

https://www.omega.com/googlebase/pr...WS4gkaoZVe5ZK9oQ8G6hvXgw4oYfyQABoC-PAQAvD_BwE

It's unfortunate that you've already built circuits around a different sensor choice, but if I were in your shoes I'd just start over with more suitable probes and build a circuit to match.

You can buy USB thermocouple data logging devices, or roll your own with an Arduino. There are integrated circuits that do most of the work for you, and there are pre assembled breakout boards that get you even closer. I've used these with great results in several projects.

https://www.adafruit.com/product/17...t5En9dnH5F1Db5d9kndpyVV1WOZWXo6BoCntAQAvD_BwE

As others have pointed out, initial thermocouple accuracy isn't what you need, but neither are your thermisters, so what's the difference? Either way, you'll need to do your own calibrations.

I could be way off base. Best of luck no matter which way you go!
 

Reloadron

Joined Jan 15, 2015
6,216
Ron, yes I believe that the ones we have are Type T thermocouplers. As I understand, for those to work, I would need to have amplifiers installed to read them whereas thermistors are pretty straight forward. I already have made the PCB to record from 8 probes onto a SD card. So the only thing that I'm struggling with is the probe design...
Displaying a temperature using a Type T or really any common thermocouple is really relatively easy and not as expensive as it once was. Thermocouples are chosen based on the task at hand, things like sheath material (if a sheath is used) wire gauge and the list goes on. That being true of just about any temperature sensor be it thermocouple or other. While for some applications plus or minus a few degrees uncertainty is acceptable for other applications much tighter tolerances are required. You ultimately decide what best suits your needs and yes, cost is also a factor. Each type of sensor offers some good and some less than good advantages.

Sometimes it is also easier to buy than build a temperature monitoring system offering up more possibilities.

Ron
 
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