Let’s talk about tilt sensors for a second. The simplest tilt sensors – the dead simplest – are a few ball bearings rolling around in a small metal can. When the can is tilted, the balls roll into a pair of electrical contacts, completing the circuit. How about a drop of mercury in a glass ampule with a few contacts? Same thing. You can get more expensive tilt sensors, including a few that are basically MEMS gyros, but they’re all pretty much the same. For [Aron]’s project for the Hackaday Prize, he’s come up with a tilt sensor that is so clever, so innovative, and so elegant, we’re gobsmacked by his creativity.
Instead of electrical contacts or gyroscopes, [Aron] is using induction to measure the tilt of a sensor. By wrapping a tube with one long primary winding of copper wire, and several secondary windings in various places, [Aron] built a Linear Variable Differential Transformer. If you insert an iron rod inside this transformer, different voltages will be induced in the primary. Simple, and this device is effectively a position sensor for any ferrous material.
Now for the real trick: put ferrofluid in the core of that transformer. Liquids always find their level, and different tilts will induce different voltages in the primary. Brilliant.
This toroidal linear variable differential transformer, when filled with ferrofluid, can measure three hundred and sixty degrees of tilt to an accuracy of one ten-thousandth (0.0001) of a degree. That’s shockingly good resolution for any tilt sensor, and it can do it through a full rotation.
We’re always amazed by the project on Hackaday.io, and especially the project entered in this year’s Hackaday Prize. What [Aron] has done here is so clever, and so elegant, we’re shocked we haven’t seen this before. Finally – a use for ferrofluid besides playing with magnets.
You can check out the video demo of [Aron]’s torridal tilt sensor below.