This document discusses different types of touchscreen technologies and recent advancements. It describes four main types: resistive, capacitive, infrared, and surface acoustic wave. Capacitive touchscreens using indium tin oxide electrodes are now most common due to low cost and good image quality, but ITO is becoming expensive and brittle. Graphene has potential to replace ITO as it is more flexible and durable, but mass production of graphene for touchscreens remains challenging due to the difficulties of growing defect-free graphene sheets and transferring them to device substrates.

1. WORKING OF TOUCHSCREENS
AND LATEST ADVANCEMENTS
KAUSHIK BARO

2. TYPES OF TOUCH PANELS
1.RESISTIVE
2.CAPACITIVE
3.SURFACE ACOUSTIC
4.INFRARED (IR)

3. INFRARED (IR) TOUCHSCREENS
 Infrared monitors use IR emitters and receivers to
create and detect invisible grid of light beams across
the screens.
 When an object interrupts the invisible infrared light
beam the sensors are able to locate the touch point.
 This ensures best possible image quality.
DISADVANTAGE:-
 The infrared beams are above the screen and the
screen may get
accidently activated because of dust or other object.
 Higher cost

4. SURFACE ACOUSTIC WAVE
 Touch screen monitors have a series of piezoelectric
transducer and recievers along the sides of monitor’s glass
plate to create invisible grid and ultrasonic waves on the
surface.
 When a panel is touched , a portion of wave is absorbed .
 This helps receiving transducer in locating the touch point.
DISADVANTAGES:-
 Water droplets may cause false triggering.
 Solid contaminants can create false triggering.

5. RESISTIVE TYPE TOUCHSCREENS
 A resistive touch screen monitor is composed of a glass
panel and a film screen
 Each layer is covered with a thin metallic layer,
separated by a narrow gap.
 When user touches the screen , the two metallic layers
make contact, resulting in electrical flow.
 The point of contact is detected by this change in
voltage.

6. CAPACITIVE TYPE TOUCHSCREENS
 Most popular type of touchscreens.
 A transparent metal electrode layer is placed on the top of
glass panel, and covered by protective cover.
 low voltage and high frequency electrical signal is applied
across electrode.
 This forms alternating electric field across the screen.
 When we touch we make capacitor(our body is a conductor)
with the electrode.
 Thus small current flows through our finger(our body is a
conductor).
 This small change is noticed by controller.

7. Electrode Material Used
 Indium Tin oxide(ITO) is used as electrode(thin film).
 It is ceramic and hence brittle, but making it nano-meter level thin
gives it a bit of flexibility.
 Made by D.C Magnetron sputtering.
CHALLENGES:-
 ITO is becoming costly.
 Works well on glass.

8. The material that can defeat the problem is GRAPHENE

10. CHALLENGES
• Mass production.
• Making of graphene sheet is costly(epitaxial growth
on SiC, CVD).
• Defects are unavoidable.
• Transfer of graphene sheet to other substrate is a
difficult process.(why can’t we grow on that substrate
itself? (misfit)).
• Metal act as catalyst in CVD, therefore insulators are
avoided.
THE END

11. THANK YOU !!