# What type of temperature sensor is this?

I have a bunch of these temperature sensors that I want to use for a project, but I can't find any information about the specifications of it. There are no markings on it to aid in identification.

I have hooked it to a multimeter, and it appear to be a simple varying resistance. At body temperature it reads about 6.5kΩ, and at room temperature about 11kΩ. Is it simply a variable resistance?

• Actually u got two points (X,Y ) (body temp , 6.5 K ) , (room temp , 11 k) from this points you can get equation : R(resistance)= A * Temp + C (linear equation , A & C are constants ) So no need for the datasheet , except finding the max rating Feb 13, 2012 at 20:18
• Yes indeed, but I wanted to a) be sure this is actually a 'real' measurement and not a side-effect, and b) find out what the limits and performance of the part are. Doesn't need to be 100% perhaps, but be nice to at least have an idea it's correct. Feb 13, 2012 at 20:23
• I's good to look for the datasheet, but doubling its value for about 10 degrees of temperature seems showing that is a NTC (Negative Temperature Coefficient) thermistor Feb 13, 2012 at 20:32
• Great, that helps - it looks exactly like a bunch of other "Thin Film NTC Thermistors" out there. Feb 13, 2012 at 20:43
• @xsari: A linear approximation is not usually very good for these kinds of thermistors. If I remember right, the real equation based on the physics is exponential based. Over human range temperatures, a third order polynomial is usually good enough. Feb 13, 2012 at 21:30

What you have is a Kapton-laminated/Kapton-encapsulated thermistor. From the description, it is a NTC (negative temperature coefficent) device.

(Kapton is the material the amber film is composed of. It's a high-temperature polymer)

The actual packaging is fairly unusual. The only place I have ever seen thermistors like that is in computer sensing hardware. I also did not have much luck finding places where you can purchase similar devices.

For what it's worth, this is actually not a thin film device. It's a standard thermistor, packaged in a film enclosure. Thin film, in an electronics context, typically means that the resistive/active element is composed of a thin film, generally deposited on a substrate, typically with a vacuum deposition process.

In this case, you have a standard chip-type thermistor, which is laminated into a polymer film.

As an aside, if the part has no marking on it, you will likely never find a datasheet for your particular part. However, from the values you specify, it sounds like a bog-standard 10K thermistor (e.g. 10K @ 25°C, which is a common way to specify them), so it should be easy to use even in lieu of having a real datasheet.