Glass: Heating and Sensing Temperature

As part of a glass workshop exploring craft and digital technology, I experimented with resistance wire (NiCr).  Two successful experiments involved generating heat (top left) and measuring a change in temperature (top right).

Both experiments involved placing the wire between two sheets of glass and fusing them in the kiln.  Here I used what glass makers call a full fuse, were both sheets of glass become molten and melt together, rather as merely bonding (tact fuse).  Importantly the resistance wire survived the firing process intact.  When current was applied to the resistance wire using a power supply heat was generated, as expected.  This radiated quite quickly through the thin glass (around 3mm per sheet) and was localised around the resistance wire itself.

If you wish to control the heating process you can use a transistor and simple Arduino circuit as outlined on Bildr.

In a second experiment, I combined resistance wire with copper wire. These were tied together and embedded in the glass to create a thermocouple (can measure temperature) at the point where the two dislike metals make contact. If you create a potential divider you are then able to measure a change in voltage and therefore temperature.  For example, there was a significant change in voltage when boiling water was poured on the glass.  Here is a nice tutorial for reading an analogue sensor like the thermocouple.

The next step might be to combine both heat and the thermocouple to control temperature, as well as exploring different patterns and interactions.