Looking for Gel type Phase Change Thermometer

I am looking for a "gel" type phase change thermometer (material). It should change its color as the termperature changes.
It will be used to make a phantom for ultrasonic imaging system. When ultrasonic waves travel thru the phantom, it will change the temperature inside the jelly-like phantom. I want to observe the inside temperature change itself. I mean I am going to simulate how much the ultrasound cause the temperature change in human flesh. So the gel type thermometer(material) which can change its own color should be the best one for me.
Does anybody have idea where I can find those kind of material or device?
Thanks, Hyeonsoo Chang
==========================Research Assistant
Image Guidance Lab School of Medicine Stanford University
snipped-for-privacy@stanford.edu ==========================
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.