Ateneo Photonics Laboratory develops flexible gratings from ‘salagubang’

by Dr. Nathaniel Hermosa (Imprints of Philippine Science)

Fig. 1.  Salagubang immersed in elastomer from R. Guerrero et. al., Material Science and Engineering C (in press)Fig. 2. Elastomer after lithography (R. Guerrero)

Fig. 3.  SEM images of the beetle structure and the elastomer-replicated structure. Magnified replicated structure is also shown. (R. Guerrero)

Nature is a rich source of interesting structures.  In  their soon-to-be published paper in Materials Science and Engineering C,  R. Guerrero and E. Aranas fabricated a unique and flexible optical grating with a beetle carapace [1].Biomimetics or biomimicry is a principle in process or design in which nature is the source of inspiration.  There have been a lot of work in optics in this area.  Most notable are the fabrication of photonics crystal lattices and multiple gratings.  The production of these structures has been cumbersome however,  requiring for example electron beam etching.In their work, the authors apply soft lithography via elastomeric casting.  Soft lithography is known to have good replication accuracy.  This enables them to copy the surface structures of the Philippine beetle Chrysochroa fulminans cobaltina at relative ease.   This beetle’s surface displays  subtle coloration which indicates that the surface can ‘play’ with an incident light.

The method is fairly simple and straightforward.  The beetle was fixed on a custom mold with its ventral side up while a liquid silicone was poured on it.  As soon as the elastomer was cured,  it was carefully peeled off from the beetle.  SEM images were obtained to verify if the structures are indeed replicated.

The authors also studied the intensity pattern when light from a laser is made to pass the structures.  This is to check if the replicated structures can be used for optical processes.

The authors add that the potential of soft lithographic techniques in fabricating tailored optical surfaces based on biological templates may find use as unique diffractive elements.

This research was supported by the Philippine Council for Advanced Science and Technology Research and Development (PCASTRD-DOST). R. Guerrero and E. Aranas are from the Ateneo de Manila University Physics Department.

[1] R. Guerrero and E. Aranas, Diffraction from relief gratings on a biomimetic elastomer cast, Materials Science and Engineering C (article in press) 2010.  DOI: 10.1016/j.msec.2010.06.017


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Physics News and Features from Ateneo de Manila University

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