2. Prototype Showcase  What is a metamaterial?  How our 2-D sample was created  How our phase mask was created  SEM images of 2-D sample and phase mask

3. Metamaterials A periodic material that has photonic or phononic properties. *Taken From 3.042 handout & Physics Worlds 2005 “Sound Ideas”

4. Deliverables  3-D periodic structure with micro- scale periodicity  Macro-scale representations of the structures

5. Prototype Design 2-D structure  phase mask  3-D structure 2-D structure: 2 microns thick, 5 microns thick, 15 microns thick Variable spacing 3-D structure: Very thick (~50 microns) Variable spacing

6. Contact Lithography Coat Exposure Develop plain Si wafer coat with HMDS to make Si wafer hydrophobic coat with SU-8 2015 photoresist using spin coater soft bake @95° to evaporate solvent and cut into pieces UV exposure for either 15, 20, 25, or 30 seconds flip 90° and expose again post bake at first 65° then 95° to promote crosslink formation submerge in PM acetate to dissolve unexposed photoresist (20 min ） submerge in isopropanol to wash away all remnants—final structure

7. Phase mask Step 1 Step 2 Step 3 Vacuum sample with open bottle of fluorosilane so that it evaporates onto sample. Layer with PDMS and heat at 65°to 75°for at least three hours. Gently peel off PDMS layer as phase mask.

8. Fabrication and Processing SU-8 2002: 15 seconds, 20 seconds, 25 seconds SU-8 2005: 25 seconds, 30 seconds, 35 seconds, 40 seconds SU-8 2015: 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds Type of Photoresist

9. Prototype Functionality Thick Film Photoresist Sin (70) = 58 / t Calculation: Thickness (t) ~ 61 microns Success!

10. Prototype Functionality 2-D Patterns Top-down view: Hole Spacing ~ 3.38 um Hole Length ~ 1.56 um Hole Height ~ 1.54 um Cross-section view: Width of top ~ 1.81 um Width of bottom ~ 1.00 um Height ~ 10.00 um

11. Prototype Functionality Problems in 2-D patterns 1.Over exposure 2.Un-washed monomer 3.Non-uniform columns Width of top ~ 1.81 um Width of bottom ~ 1.00 um

12. Prototype Functionality Phase mask

13. ? 2-D Pattern Phase Mask3-D Pattern CAD Model 3-D Printing Model Actual Sample

15. Questions?