A Temperature-Sensing Magnetic Stir Bar

Magnetic stirring bars are the coolest piece of equipment you’ll see in a high-school chemistry lab. They’re a great way for agitating a solution without having to stand there manually and do it yourself. [Applied Science] has now made a magnetic stir bar that features an integrated temperature sensor.

The device is essentially an RFID temperature sensor snuck inside a custom-made magnetic stir bar. The bar is paired with a smart hotplate base that displays the temperature readings. As a bonus, it can detect when the magnetic stir bar is out of place or not in sync, prompting it to slow down the spin motor until the stir bar is turning properly again.

The video also notes that the stir bar could be instrumented for even greater functionality. A Hall effect sensor could measure the magnetic slip angle of the stir bar, and provide useful readings of liquid viscosity. Alternatively, a pressure sensor in the stir bar could potentially measure liquid level based on hydrostatic pressure.

It’s a great quality-of-life improvement for regular lab work. It eliminates the need for bulky temperature probes that often get in the way. We’ve featured some interesting temperature sensors before, too.

6 thoughts on “A Temperature-Sensing Magnetic Stir Bar

  1. Clever. although a bit over-engineered, but most important : how long will it survive the heat / how much heat can it take ?

    Like for example you´re preparing an in-vitro culture medium, you got to cook the purified agar-agar with distilled water and nutriments, bringing the whole to boiling before filling your test tubes or Erlenmeyer vessels.

    1. The obvious answer is to use military and/or aerospace rated semiconductors.

      The problem with this is that they can be difficult to obtain and bloody expensive to boot.

      1. No joke! I was trying to find some darlington arrays yesterday and found some milspec ones that were $75/100 and I thought, huh, that’s not a terrible price, only about twice as expensive as the ones I wanted that weren’t in stock, so I clicked on it and realized, no, they were $75 _each_, minimum order of 100.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.