design principles of bacteriorhodopsin imaging systems jussi parkkinen department of computer...
TRANSCRIPT
Design Principles of Bacteriorhodopsin Imaging Systems
Jussi Parkkinen
Department of Computer Science
University of Joensuu
Finland
Co-authors
• Timo Jääskeläinen optics • Sinikka Parkkinen molecular biology
University of Joensuu
• Lasse Lensu information technology
Lappeenranta University of Technology
• Michael Frydrych computational engineering
Helsinki University of Technology
Outline
• Background
• Biological vision systems
• Basics of bacteriorhodopsin
• Design of bacteriorhodopsin based color vision system
• Conclusions
Outline
• Background
• Biological vision systems
• Basics of bacteriorhodopsin
• Design of bacteriorhodopsin based color vision system
• Conclusions
Visual pathway
• Detecting of the color signal– cones and rods
• Preprocessing in the retinal level– horizontal cells, amacrine cells, bipolar
cells, . . .
• LGN level (6 layers)
• Visual cortex (108 cells)– other areas of cortex
Design of sensitivity function
• Sensitivity functions over spectrum– optimal functions
– not realizable on molecular level
• Spectral band detectors– separate bands covering the spectrum
– natural on molecular level
• Artificial vision systems important
• Organic and biomolecules gaining interest in electronics
• Biological systems– object of research– source of innovations
• We study color vision systems and use biomolecules in a test system
Outline
• Background
• Biological vision systems
• Basics of bacteriorhodopsin
• Design of bacteriorhodopsin based color vision system
• Conclusions
Bacteriorhodopsin
• Membrane protein of Halobacterium salinarium
• Halobacterium salinarium lives in very salty waters
• Isolated by Oesterhelt and Stoeckenius in 1974
Why bacteriorhodopsin?
• photoelectric
• stable and long lifetime
• easy to produce
• possibility to modify the molecule
• > 106 reversible cycles
• Resolution > 5000 lines/mm
Bacteriorhodopsin applications
• Optical 3D memory Birge
• Optical recording media Hampp
• Optical sensor matrix Koyama et al.
• Color sensor Parkkinen et al.
Outline
• Background
• Biological vision systems
• Basics of bacteriorhodopsin
• Design of bacteriorhodopsin based color vision system
• Conclusions
Preparation of BR/PVA-films
Purple membrane was used
1. Mix Polyvinylalchohol (PVA) with
BR-solution
2. Spread on a conductive glass
3. Let dry 24 hours
4. Sputter gold layer on the film to be
the counter electrode
Outline
• Background
• Introduction to spectral color
• Biological vision systems
• Basics of bacteriorhodopsin
• Design of bacteriorhodopsin based color vision system
• Conclusions
Conclusions
– The photosensitivity of sensor is not very high
– Differencies of timedelays between retinal analogs causes application dependend problems
Conclusions
+Bacteriorhodopsin is a photoactive protein for color sensor
+Protein based system is build, which learn it’s own color space
+The detectors are easy to produce
+Flexible shaped sensor possible
+Color filter embedded in sensor
Acknowledgements• Professor Dieter Oesterhelt
for original BR
• Dr. Andrei Khodonov
for retinal analogs
• Mr. Juha Juuti and Ms. Helvi Turkia
for technical assistance
• The study was financially supported by
Academy of Finland and TEKES/Finland