Can You Heat Me Now? Brie Frame Sandra Gonzalez Angela Tong Chenny Zhu Department of Materials Science Advisor: Hao Wang March 4, 2004

Outline of Presentation Objective Updated Design Potential Materials Proposed Schedule

Objective Design and fabricate a heat therapy device for lower back pain with a future use for transdermal drug delivery.

Single Component vs. Hybrid ChemicalElectricalHybrid Portability +—+ Low Cost +—— Modular +—+ Temp. Regulation —++ Compact +—— Long Heat —++ Reusability —++

Components of Device Body Outer Covering High Insulating Layer Heating Core Battery

Device Placement Heating Device Battery

Heating Core Potential Materials  Tetradecanol  Ethylene Carbonate  2,6-Di-tert-butylphenol  Cis-Cyclohexane-1,2- dicarboylic anydride  Benzylideneacetone  Sodium Acetate

Insulating Material Potential Materials  COHRlastic Solid Silicone Rubber Thermally Conductive R10404  Low Thermal Conductivity W/mK  Very Thin R10480  Low Thermal Conductivity  Flexible  Cotton Low Thermal Conductivity 0.03 W/mK  Neoprene  Insulwrap Quilts from American Acoustical Products

Battery Sanyo Batteries  Lithium Polymer: UPF high energy density both by volume and by weight, flat and flexible not as much total energy available per battery  Li-ion Rechargeable: UR18650H, UR18650F highest energy densities of the fifteen batteries surveyed less total energy than lithium polymer, round casing Saft Batteries  Li-ion Rechargeable: MP and others highest total energy available per battery, flat casing big and bulky, rigid casing, low energy density

Switch Potential Switches  Polymer Thermal Switch Polymer matrix with conductive particles interspersed When cooled, matrix becomes compact, particles touch and form electrically connected network When heated, matrix expands, connected network breaks  Bi-metallic Switch Two metals with different expansion coefficients laminated together When heated, one expands more than the other, which causes it to bend and either open or close the circuit  Integrated Circuit – Programmable Thermostatic Switch Circuit where temperature setting can be controlled by adding resistors

 Ni80Cr20  Ni60Cr40 High Resistance Strong Cross-sectional area = 1.26x10 -3 sq. in. Wire Tensile Testing

Wire Tensile Results for Ni60-Cr40 Ultimate force withstood: 135 pounds Ultimate Tensile Strength (UTS): 107,432 psi Elastic Modulus= (61,674-15,915) psi / ( ) = 1,322.5 ksi Total Elongation=1.9 in.

Wire Tensile Results for Ni80-Cr20 Ultimate force withstood: 160 pounds Ultimate Tensile Strength (UTS): 127,300 psi Total Elongation=2.6 in.

Proposed Schedule