Unit:
Κατεύθυνση Επιστήμη Πολυμερών και Εφαρμογές τηςLibrary of the School of Science
Author:
Γεωργάκη Μαρία-Ισιδώρα
Supervisors info:
Μαργαρίτα Χατζηχρηστίδη Λέκτορας ΕΚΠΑ
Original Title:
Ανάπτυξη πολυστρωματικών υμενίων και εφαρμογή τους στη φωτονική και τους αισθητήρες
Summary:
In the present thesis the fabrication and characterization of one dimentinal
photonic crystals for two different applications is presented: as chromic
humidity sensor and as a narrow wavelength filter.
The 1D photonic crystals consist of alternative films of two materials having
different refractive indexes. The fabrication of the photonic crystals was
based on commercial polymers: poly(2-hydroxyethyl methacrylate) (PHEMA),
poly(methyl methacrylate) (PMMA) and an negative chemically amplified epoxide
based photoresist (EPR) that was synthesized in our lab. In order to increase
the refraction index difference of the materials, a titanium dioxide solution
was mixed with the EPR resist.
The polymeric photonic crystals were fabricated using conventional lithographic
techniques. The characterization of the samples was made by optical methods
based on white light interferometry.
When the PHEMA-EPR (humidity sensor) sample is situated in a humidity
environment, the hydrophilic PHEMA film swells giving a red-shift on the
reflectance peak of the photonic crystal and thus the sample changes color.
This sample is a humidity sensor that does not require any external power. The
swelling of the hydrophilic film is a reversible and reproducible phenomenon
since the whole process is based on physisorption of water molecules. It is an
easy and low cost fabrication.
The polymeric materials PMMA and EPR (narrow wavelength filter) are
photosensitive resists and thus are capable of fabricate photonic crystals of
diverse patterns.
Keywords:
Photonic crystal, Polymers, Humidity sensor, Swelling, Optical methods
Number of index pages:
15-19
