Revolutionary Color Filtering Using Fluorescent Polystyrene BeadsBRIAN GALLASPY ALAN PHAM

HUAYU ZHOU SACHIN MEHTA

Introduction• Using solutions polystyrene beads of the following colors: red, blue, and green we will print 5mm x 5mm

squares on photo-paper.• Various combinations will be printed—layer on top of layer. For example, some of the combinations:

• Red Blue GreenRed Green Red

Green OR Red OR BlueGreen Blue

• These combinations, when analyzed using Photo-Luminescence Spectrometer from Ocean Optics, will result in different spectrums and wavelengths.

◦ The variable is the amount of layers of a certain color we put in a sample.

◦ These wavelengths will then be plotted on the C.I.E Chromaticity Diagram System.

C.I.E 1931 Color Space Links physical pure colors (wavelengths) & perceived color of the human eye

Three ‘primary’ colors—red, blue, and green

Characterizes colors by a luminance parameter Y and a two-coordinate x,y system—which specifies any single point on the chromaticity diagram to the right

The various color combinations printed one on top of another will allow us to develop our own Chromaticity Color Triangle

Photoluminescence• Certain molecules are capable of absorbing energy from photons (UV, vis.)• Energy is absorbed by electron moving to unstable “excited state”• When the electron relaxes to ground state, energy is released as a photon corresponding to the difference in energy between excited state and ground state

Picture taken from Wikipedia.org Photo taken from pubs.rsc.org

Photoluminescence cont.

• Molecules that fluoresce contain conjugated π- bonds• This means that the molecule has a structure that has alternating

single and double bonds• This structure allows electrons to be shared throughout the whole

molecule, and energy states that are conducive to fluorescence

Picture taken from Wikipedia.org Picture taken from Wikipedia.org

Fluorescent Polystyrene microspheres

• Polystyrene is a widely used polymer of the monomer styrene• It can be made into spheres ranging from 1μm – 1mm• Upon these spheres, fluorescent compounds are attached

Picture taken from lifetechnologies.com

CIE color spectrum

• Shows all colors perceptible to human vision• Each vertex represents red, green, and blue, which correspond to

long, medium and short wavelengths• All colors perceptible to humans are represented on the chart

Materials Fuifilm Dimatix 2D inkjet Printer

Fluoresbrite® Fluorescent Microspheres purchased from polysciences.com

Glass slide is used as our printing substrate

Ocean Optics Photo-Luminescence Spectrometer

Methodology Using the Dimatix 2D inkjet printer, multiple layers of the fluorescent microspheres are printed onto a glass slide. Varying layers of the three different fluoresced microspheres will yield a unique respective position on the C.I.E Color Space. Each square will then be analyzed with the assistance of Dr. Zhou, and a Photo-Luminescence Spectrometer by Ocean Optics.

Substrate Selection We determined that using a 1inch by 1inch square glass slides is the best substrate to use because the UV light can pass through the glass rather than be absorbed. We used photo paper but a had a polymer material on the surface of the paper that caused the paper to absorb the UV light This caused the printed sample to be flooded with background noise from the paper.

Photo-Luminescence Spectrometer from Ocean Optics

Using Dr. Zhou’s UV-Vis spectrometer gives us the wavelength at which each printed square absorbs.

Using this information, Dr. Choi provided us with a program using MatLab to give us the coordinates relative to the CIE chart.

Using these coordinates will tell us what the true color of the sample with the CIE chart.

Experimental Results (UV-Visible Spectra)

1 2 3

4 5 6

Nozzle ProblemsQ: What’s the current issue?

• When we change the cartridge with different solution, the number of available sequential nozzles changes as well, no guarantee that we can always have enough nozzles to use. So, for last Friday's experiment, we had to apply few nozzles, and the printing speed was restricted.

Possible solution: waveform (it controls the driving signal)

property of the printing material(try to dilute the solution)

temperature setting

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Future Direction

1. Figure out the above issues in order to obtain better results

2. Using existing experiments results (spectrums) to find the possible reasonable proportions of R,G, B beams for making synthetic pure white.

Questions?