What type of temperature sensor is this?
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.