Solar energy harvesting in the epicuticle of the

Oriental hornet

Marian Plotkin Ph.D.

National University of Singapore

Nanoscience & Nanotechnology Initiative

The Oriental hornet worker digging activityThe Oriental hornet worker digging activity

Correlation between worker digging activity

and UVB radiation

Brown Cuticle

Yellow Cuticle

Epicuticle

Epicuticle

Exo-Endocuticle

Exo-Endocuticle

Hypocuticle

Hypocuticle

Melanine

Xanthopterin

1 2 3

The development of pigments within the cuticle

Brown

CuticleYellow

Cuticle

Yellow

Cuticle

After removal

of yellow pigment granules

Liver-like enzymatic activity within the

layer of yellow granules

Measurement of voltage between the epicuticle

and the hypocuticle

Base (nm)

Base (nm)

Atomic force microscopy of the epicuticle

M

M

The internal structure of the cuticle

Epicuticle

Reflectivity measurements

2

1

3

2+3

Flat surface

A B

DC

Optical modeling of reflectance of brown and yellow cuticle

Optical modeling of brown epicuticle

as a diffraction grating in transmission

Dye Sensitized Solar Cell (DSSC) with Xanthopterin

Jsc=0.858 mA/cm2

Voc= 564 mv

FF=69.2%

Conversion efficiency= 0.335%

The cuticular multilayered structure compared to a man

made antireflection coating

Discussion

1) The Oriental hornet cuticle exhibits antireflection and light trapping properties.

2) Measurements show that the complex layered structure increases the

antireflective effect. The cuticular multilayered structure may introduce a

gradual change in effective refractive index by varying the proportion of chitin

nanorods within the protein matrix or by altering the angle of the deposition of

chitin nanorods angle.

3) The Xanthopterin pigment acts as a light harvesting molecule.

4) The Oriental hornet correlates its digging activity with solar insolation.

The Oriental hornet cuticle is a photonic structure capable of harvesting sun

light. The pigment xanthopterin within the cuticle transforms sun light to

electrical energy which may serve the metabolic activity performed within the

pigment layer hence aiding in the digging activity.

Professor Jacob S. IshayDepartment of Physiology and Pharmacology, SacklerFaculty of Medicine, Tel-Aviv University.

Professor David J. BergmanSchool of Physics and Astronomy, Raymond and Beverly Faculty of Exact Sciences, Tel-Aviv University.

Professor Arie Zaban and Idan HodInstitute of Nanotechnology & Advanced Materials, Department of Chemistry, Bar Ilan University.

Dmitry GalushkoDepartment of Physics, Technion, Israel Institute of Technology.

Professor Darren M. Bagnall and Stuart A. BodenNano Research Group, Electronics and Computer Science. University of Southampton, United Kingdom.