Smart Photonic Crystal Optical Sensors
Prof. Bettina Lotsch, Department for Chemistry and Biochemistry, Ludwig-Maximilians-Universität (LMU)
Background: In recent years, photonic crystal (PC) research has risen to the challenge to not only provide platforms for guiding and confining light with a high level of control, but also to create photonic crystal sensor platforms exhibiting a tunable optical response as a function of environmental changes.1 Smart PCs can be fabricated by integrating suitable functional materials, which are responsive to chemical or physical stimuli such as temperature, electromagnetic fields, or pressure, into a PC backbone. The material’s response with respect to these stimuli will then be transformed into a shift of the photonic stop band and thus yield an optical read-out based on a color change of the PC (Fig. 1).1 Owing to the high sensitivity, ease of fabrication, compactness and easy read-out of PCs, the design of versatile photonic crystal sensors with a plethora of possible applications is within reach.2,3
Objectives: The goal of this project is the integration of a range of functional materials into PCs, including nanoscale particles and 2D nanosheet materials which can be fashioned into multilayer architectures as in Bragg mirrors (1D PCs), or into inverse opal architectures (3D PCs). The sensitivity of the PC to solvents and gases and thus, refractive index changes, can be maximized through using materials with high porous volumes as constituents. The project aims at the implementation of metal organic frameworks (MOFs) and zeolites into PCs, and the exploration of such „photonic frameworks“ as platforms for a variety of chemo-optical sensing applications. Therefore, special emphasis will be placed on the fabrication of porous nanoparticles of various types, which when integrated into PCs will give rise to “smart” colour-coded sensors, purification, separation or gas storage devices with opical read-out.
1) L. D. Bonifacio, B. V. Lotsch, D. P. Puzzo, F. Scotognella, G. A. Ozin, Adv. Mater. 2008, 21, 1641-1646.
2 a) B. V. Lotsch, G. A. Ozin, Adv. Mater. 2008, 20, 4079-4084; b) B. V. Lotsch, G. A. Ozin, ACS Nano 2008, 2, 2065-2074.
3) B. V. Lotsch, C. B. Knobbe, G. A. Ozin, Small 2009, 5, 1498-1503.
The ideal candidate:
- Enthusiastic for an interdisciplinary approach borderline between synthetic chemistry, nanotechnology, material science and physics,
- background in chemical, materials science or physics (depending on the
background, the project will be geared towards either the design of smart PCs, sensing applications, or the optical characterization of the sensing devices), - experience in experimental chemistry and analytical techniques such as UV-vis, diffraction methods (X-ray, electron), imaging (SEM, TEM), NMR and vibrational spectroscopy.
Scope of scientific methods and techniques:
Experimental techniques:
- Inorganic synthesis (this may include handling of air-sensitive compounds, Schlenk technique, glove box etc.)
- Coating techniques, including spin-coating and dip-coating
- soft lithography
- layer-by-layer electrostatic self-assembly
Analytical methods:
- Optical spectroscopy (UV-vis)
- X-ray powder diffraction, electron diffraction
- Electron microscopy (TEM, HRTEM, SEM)
- Vibrational spectroscopy (IR, Raman)
- NMR and solid-state NMR spectroscopy
- Ellipsometry
- Porosimetry
Information about the research group:
http://www.cup.uni-muenchen.de/ac/lotsch/