I $am$ currently developing tissue phantom gels for $t$ hyperthermia treatment. I $am$ exploring with hydroxyethylcellulose dissolved $in$ water. I $am$ using a concentration $of3\mathrm{.}5\%$ hydroxyethylcellulose and $96\mathrm{.}5\%$ water $in$ a total volume $of200ml.$ When I check the dielectric properties $ofmy$ phantom I see that the permittivity $is$ high $(around75).My$ targeted permittivity $is57,tobe$ able $to$ mimic muscle tissue. $Do$ you know what other ingredients I can add together with hydroxyethylcellulose $to$ lower the permittivity $inmy$ solution? While lowering the permittivity, I also want $to$ increase the mechanical strength and solidity $of$ the phantom gel. $Isit$ recommended $to$ add $2$ more ingredients $to$ hydroxyethylcellulose? One ingredient $to$ lower the permittivity, and another ingredient $to$ increase the mechanical strength $of$ the gel. The ingredients also should $be$ compatible with hydroxyethylcellulose. Can you give some examples $of$ ingredients I can explore? Also, I want $to$ avoid the occurence $of$ air bubbles $inmy$ phantom gel $to$ recieve accurate dielectric properties. When $It$ comes $to$ the mixing process, I usually heat$\frac{2}{3}of$ the water and pour the hydroxyethylcellulose powder gradually until all the powder $is$ dissolved. Then I add the remaining$\frac{1}{3}of$ water $as$ cold water $to$ cool down the phantom gel. Should I change the mixing process $If$ I add one $or$ two more ingredients? $or$ should the process still $be$ the same? Also, $isit$ recommended $to$ pour all the powders together $or$ should I first pour one ingredient, and then the others? Thank you for the help!