High Temperature LCD Displays

This extreme environment will probably degrade any of the common liquid crystal molecules. Even if you found something that can take the heat, it would have to be hermetically sealed to protect the connections from moisture.

This is too hot even for LED displays. Can you use a vacuum fluorescent tube? This technology has somewhat higher power requirements, but if protected from the humidity, it may be able to tolerate the heat. A list of manufacturers is available at

http://www.maxim-ic.com/appnotes.cfm/an_pk/1154

Put a sensor in the steam bath, and bring the signal out to an indicator in a reasonable location!

If the display is part of a medical device that must be put in an autoclave, separating the sensor and display may not be an option. I assumed something like this would be the case when I suggested a different display technology such as VFD. Otherwise, as dkwarner suggests, it makes more sense to put the display (and signal conditioning electronics) somewhere else.

As far as a temperature-to-human-interface is concerned, the ability of a human to withstand 140degC is probably the commercially-limiting factor.

As above, put the sensor in 140degC, and bring the display out to temperate latitudes, probably using wires.

LCD's are a poor choice for the type of environment you describe.

The LC fluid would be isotropic at 140C, and would lose all of the properties that make useful for LCD displays. (some displays turn isotropic even in direct sunlight)

The expansion of the fluid at this temperature would likely cause the seal of glass sandwich to lose integrity and leak.

Also, the polarizing films would begin to distort and lose adhesion.