Biometric Sensors and the Right Epoxy

I have some doubts that you can match mass specific heat but it would be quite easy to match the conductivity (by the way the units you use are?). The dynamic behaviour could may be compensated by a circuit?

Have you searched

www.matweb.com

Thanks- good lead. The only material listed that is similar to water appears to be BASF Ultramid 8202 PA6 (Dry) [density 0.93 g/cc; specific heat capacity 3.7 J/gK; thermal conductivity 0.26 W/mK- quite a bit lower than water). Has anyone tried to make molds from small quantities (~3x3 cm) of this material?

I do not know which type of sensor you want to develop but thinking more about the body thermal behaviour I presume that the only static match with the thermal difusibility (λ/Cp*ρ) in m^2/s will not be sufficient since this way you do not take into consideration the blood convective participation which I presume is not neglectable. If you compare the two materials water and the one you found the second has a difusibility 1/2.15 with respect to water. This is too much to allow a good simulation.

I think that if you have the thermal flow at skin level between a warm/cold body and the skin it could be possible to build a dynamic simulator.

Only a thought.

I am CoronaCameraMan,

Seasons Greetings,

Have you considered "dental cement" ? There are no doubt variations of rigid and slightly flexible. These cements must be impervious to water, acids and many other chemicals. They must not contaminate there environment by off-gassing or leaching chemicals. Your base materials may need to be changed to be more compatible with the cements.

Many epoxies are not water proof and will loose there surface bond or disintegrate, including some o-ring epoxies.

Happy Holidays

Try contacting Master Bond, they have ranges of epoxies with specific thermal characteristics & an extensive range of medical grade epoxies.

You might consider talking to 3M adhesives division.

Reynolds Advanced Materials sells a variety of castable epoxy resins:

http://www.reynoldsam.com/index.php?cPath=1295_1298

The manufacturer doesn't provide conductivity data, but working samples can be ordered for ~$25.