Flexible OLED displays can be used for optogenetics by selectively activating neurons through individual pixels on a thin, biocompatible plastic substrate. The document describes how a flexible OLED display was fabricated using organic light-emitting diodes and a thin-film transistor active matrix array on a 125 micrometer plastic substrate. Experimental results showed the flexible OLED display could produce over 1mW/mm2 of blue light intensity needed for optical stimulation through pulsing. Tests also demonstrated the flexible display's biocompatibility for growing cells on its surface.

1. FLEXIBLE OLED DISPLAY
TECHNOLOGY FOR ELECTRO-
OPTICAL STIMULATION
G U I D E D B Y,
C E L I N E M A R Y S T U A R T
P R E S E N T E D B Y,
C H I N C H U T H O M A S

2. INTRODUCTION
 OPTOGENETICS: using light simulation controls the
excitation, inhibition or signaling pathways of genetically
modified neural tissue.
 Neurons are genetically modified using viral vector.
 Cells expressing Channelrhodopsin-2(ChR2) are activated by
blue light.
 Cells expressing Halorhodopsin are silenced by yellow light.
 Common approach done is to insert the exposed tip of fibre optic
cable into the brain tissue of an animal model.

3.  Newer approach replaces this fibre optic probe with
small array of discrete light emitting diode(LED).
 This approach eliminates the need for a permanent
opening in the cranium.
 One key limitation in this approach is the inability to
turn on individual pixels and also high power
consumption.
 Hence a new concept is introduced “FLEXIBLE OLED
COLOR DISPLAY”.
 They can be used on thin biocompatible plastic
substrate to selectively activate individual pixels.

4. OLED
 Organic light emitting diode.
 They are coated glass plates.
 Organic compounds used are
hydrocarbons.
 Fabricated on plastic substrate.
 these glass plates are tightly
sealed to provide protection
from moisture and oxygen.

5.  Plates are of thickness 1/1000th of human hair, providing
capability to bend over a wide variety of degrees.
 They doesn't produce heat when turned on.
 OLED technology produces self-luminous displays that
doesn't require backlighting and hence they are more power
efficient.
 OLED requires only less power, i.e. 2-10 v.
 They use substances that emit RED,GREEN and BLUE or
WHITE light.

6. FLAT PANEL DISPLAY TECHNOLOGY
 Active matrix, thin film
transistor(TFT) array
technology.
 Interconnection wires enables
to turn on individual pixels.
 32 by 32 discrete LED array
requires 1024
interconnections.
 32 by 32 TFT active matrix
array requires only 64
interconnections.

7. FLEXIBLE OLED DISPLAY TECHNOLOGY
FOR OPTOGENETICS
 Discrete array LED consists of one LED per pixel.
 Active matrix OLED displays consists of two TFT’s and
one capacitor(2TIC) per OLED pixel.
 OLED,TFT and pixel capacitor is integrated on the same
substrate.
 It emits bright light when a forward bias is applied
between a transparent anode and reflecting cathode.

8.  Conventional TFT-based flat panel OLED displays are
produced on fragile and rigid glass substrate.
 Fragile glass substrate is replaced by a flexible plastic
substrate of 125 micrometer thickness.
 Flexible OLED is very thin and transparent sheet of
plastic.
 Constructed by sequential layering and patterning Nano
scale thin films on its surface.

10. EXPERIMENTAL DETAILS AND
DEVICE FABRICATION
 the light emitted should be
bright enough to induce optical
stimulation.
 Blue light in the range 450-
460nm is the optimum
wavelength.
 Fluorescent blue OLED device
structures consists of injection,
transport and blocking layers
along with emission layer.

11.  Cathode used is a reflective aluminum surface and anode is a
transparent Indium Tin Oxide(ITO).
 Emissive layer used is a single host doped with a blue
fluorophore.
 Electroluminescence (EL) optical spectra is obtained using
Ocean optics HR4000 CG spectrometer.
 Luminance versus voltage (L-V) curve was collected using a
Newport optics 818-UV photodiode.

12. RESULTS AND DISCUSSION
High light intensity pulsed blue OLED
development
 A minimum of 1mW/mm2 of instantaneous
pulsed irradiance at a wavelength of 450nm
is required.
 The intensity is 0.1mW/mm2 for bottom-
emitting blue OLED at 7v DC bias condition.
 Pulsing the supply voltage of OLED.
 A thin 30 micro metre flexible metal foil is
bonded to the back of reflective cathode.

13.  From the figure the required 1mW/mm2 of instantaneous
light intensity is achieved at 13v,at 20Hz pulse with a
10ms pulse width.

14. Flexible OLED display biocompatibility
 Biocompatibility and long term in-vitro durability of flexible
OLED display were evaluated.
 Ability to grow immortalized epithelial cells on the surface of
full TFT-process plastic flexible display substrate.
 Blue OLED’s requires ETHANOL(EtOH) sterilization. That
doesn't make any change in the optical characteristics.
 Operating temperature at the surface of the blue optical emitters
under 1mW/mm2 pulse mode should be compatible with the
living brain tissue.

16. ADVANTAGES
 Paper like readability.
 Thin, light form factor.
 Twistable

17. DISADVANTAGES
 Very low refresh rate.
 Very slow zoom.
 Ghost images

18. APPLICATIONS
 SHELF LABEL
 Price information can be
updated
 Requires no battery
 Uses energy from RF wave

19. E-books

20. Smart card display
 Flexible as normal
credit cards

21. CONCLUSIONS
 Benefit to economy and simplify everyday life
 More applications in future.
 Additional modifications done to accelerate the
marketing.