Evolution of NRL Materials Research on Lipid Tubules

Tubules discovered at NRLDARPA ProgramMetal Clad Tubules

Field Emitting CathodesControlled Release Demos

1983-1990

1991

1994

1996 lipid wall thickness control demonstrated

March 1997 - RAM-PatentApplication6.2 NRL funding for Tubule

based RAM 1996-2000

FY04Transition to Navy SystemsNULKA...

RTP, Biocompatibles CRADA’s for controlledrelease

FY98Fabrication of prototype RAM

Chiral Models developed

CD Experiments Start

NRL Base funding for Tubules starts

Tubule-based dielectric composites (ONT)

6.2 ONR funding for Antenna Isolation 1998-2003

NULKA isolation spec met, JULY ‘00

Successful captive flight testFlorida, April ‘02

Tubule108 - 109 Molecules

Lipid Bilayer

DC8,9PC

Diacetylenic Phospholipids Synthetic phospholipids with photopolymerizable

diacetylenic moieties in their acyl chainsObserved to self-assemble into hollow, cylindrial structures = tubules

P. Yager and P. E. Schoen, Mol. Cryst. Liq. Cryst. 106, 371 (1984)

J. Schnur, Science, 262, 1669 (1993)

1 m

diameter ~ 0.5 mlength ~ 10 - 100 m

Approach: High Aspect Ratio Microtubules

Bio-derived tubules: 0.5 micron diam. x 10’s micron length High conductivity electroless copper coating Small dimensions vs RF wavelength yield high dielectrics

Release from Lipid Based Tubules

• Larger diameter (0.5u)• Aspect Ratio 10-200• Lipid or Metal Coated• Some control of structure

possible• Rational control of release

demonstrated• may be utilized in multi-purpose

coatings • May be used to entrap

– nanoparticles– higher molecular weight polymers

• Demonstrated effectiveness over 1 year in field conditions

• Subject of 2 CRADA agreements

Artificial Dielectric Panels

Random dispersion of microscopic metal rods in

polymer

Bioderived microtubules: small size leads to broad

bandwidth

Per

mitt

ivity

Volume loading

real

imaginary

Lossy at low loadingsLightweight composites

Permittivity nonlinear with loading density

Surface Wave

RF propagation schematic: antenna coupling

Gain limited by feedback

Receive Send

Test fixture (decoy)

Light weight panels longer dwell-time increased payload

Tested and accepted by Sippican Inc.

Successful Captive-Carry test in Florida, April 2002

NULKA Decoy