Walmart tags
-have RFID which scans item into inventory
-fully printed (more cost effective)
the key element
the chip/brain
key of processing
transistors
transistors are and consist of
-semi-conductor device
gate
dielectric
semi-conductor
substrate
obstacles
-finding the right materials, not too rough
-develop better printed products NOT traditional print (aka additive manufacturing)
-subtractive is etching (lots of chemicals and waste)
picture of metal lines and chip
-transistor- covered in clear silicone protector
-the lines are charging
-the yellow clear over is the insulator-underneath the antenna
flexible hybrid electronics
-electronics for human monitoring
-can stretch
what do we need to make things work
CONNECTIVITY
bluetooth, wifi nfc
SENSING
POWER
-batteries, charging
modules are
building blocks
the main goal *
printing conductive materials on flexible materials
what is the ideal substrate
-flexible and lightweight most desired
polymer substrates
+: inexpensive, flexible
-: low thermal/mechanical stability, will melt
polymer film categories
pre-stabilized film: controlling heating and cooling to rearrange polymer chains
-semi crystalline-PET, PEN
amorphous-PC
amorphous solvent cast-PI
polymers
are chain like molecules with repeating structures (monomer isn't connected)
polymer morphology
the molecular arrangement
amorphous-very stable, doesn't change with heat (looks all jumbled, polyimide)
semi-crystalline-patterned, sharp melting points
tg and tm
glass transition temperature-softens/gooey
melting temperature
youngs modulus
measures force per unit area that is needed to stretch or compress a material sampleIt defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material.
nm/2 or psi
tension modulus/modulus of elasticity
describes stress/strain relationships
stress/strain
coefficient of thermal expansion
-change in length per unit length of material per degree of temp. change
mechanical stability
high youngs modulus
low cte
residual stress
frozen in stress
-flow induced
-molding polymer parts
-thermal induced (cooling to form parts)
permeability
important parameter for OLED, photo voltaic devices
permeability rate: the rate at which a gas or vapor passes through a polymer
-want semi crystalline over amorphous
-can improve resistance with barrier
-PET and PEN (polyethylene, high permeability, SEMI
PET and PEN
PET: packaging
PEN: not clear, hazy, high tm high glass transition
high permeability: need to protect against oxygen and h2o
standard packaging film vs electronic grade film
standard: rough, bad, spiky
electronics: smooth, needs to be clean of dust
laminating dupont film: middle, flat but bumpy
metal substrates
-rare, flexible, good heat resistance, conductive
high young modulus, COSTLY
paper substrates
+: low cost, disposable, low thermal expansion
NEEDS SURFACE TREATMENT to reduce absorbency
-low end products: simple circuits, disposable sensors
biggest challenge
-surface roughness, porosity (can be improved by coating and calendaring)
dimensional stability (paper substrates)
-degree to which substrate maintains dimensions when subjected to change
-needed for registration accuracy
mechanical flexibility: no cracking when being folded
-special formulated papers-coating fibers
photo- more cracks, traces broken
pulp-less cracking
glass substrates
-best transparency
-low haze
-very smooth
-high process temperature
-high dimensional stability
-impermeable against oxygen and h2o
-scratch resistance
-insulator
-:fragile, heavy weight, costly, NOT AS FLEXIBLE
TPU
thermoplastic polyurethane
tm 160-190
carrier for flexible, stretchable wearble electronics
-adhesive
print materials
-printing or painting, works for either
-liquid or paste form necessary
-needs to maintain functionality
conductors
printed conductor- most common
thick film electronics-printed circuit boards
-silver flakes mixed with binder
-form percolated network
-lower conductivity than metal
conductive materials at nano scale
-incapsulated in organic ligand
-particles require sin
printed with silver flakes
for larger format prints
-not super efficient or high quality
-flakes stack which make the percolated network
functional materials
conductors
-metal, transparent (polymer(nano-wire) or inorganic), carbon
semi conductors
dielectrics
other
film vs flakes
film has higher conductivity than flakes
so does nano materials
Silver flakes are used for printing conductive traces.
nano materials
gold, silver and copper
-CAN be formulated into conductive inks
transparent conductors
touch screens
- polymer based
PEDOT:PSS (mixture of two inomers, conductive polymer) : poor performance, less transparent
PEDOT:PSS is polymer-based conductor. It is often used as transparent conductor to replace ITO. ITO has limited supply and also less
carbon based
cheaper!
graphene
-thinnest form of carbon
-transparent and strong
-excellent conductivity
-cheaper than AG
-difficult to form inks with
carbon
graphite
-good conductor, very stable
Graphene has higher conductivity than graphite, because of the sheet stru
metallic nano particles
-different shapes of nanoparticles
nano wires
metallic
-one dimensional
-used for transparent conductor
-difficult to print-coat the surface, can etch
bond together on cross pathways
basic mechanism
conductive inks require pathways for electrons to transfer
-printed conductive inks rely on contact between conductive materials
percolation threshold
critical point of volume fraction which can create continuous pathways for electrons to transfer
theory: need enough particles for path for electrons to go through, cure, solvents evaporate, particles in contact, close & strong
measuring conductivity
ohms= resistance
measured by multimeter
MEASUREMENT RELEVANT TO DISTANCE
bigger resistance-less conductivity
measuring sheet resistance
ohm/square
four point probe
dimensionless, doesn't matter what is squared
semi conductors
-either conductive or insulating
-organice based-n type or p type
usually air stabled n type
inorganic-not air stable, saline
conductive oxide- stable in air
non conductive materials
aka insulators
-keep wires separated in multi layer structure
-don't want to put more wires over it or you will short it
DO NOT connect the dielectric and insulator
if silver and carbon overlap, you will short circuit
breakdown voltage (non cond. continued)
-too much power, air is non conductive, break down the air and it becomes conductive
low breakdown voltage: concern of thin layers of dielectric material
HOMOGENOUS layer is important
any divet or crack in dielectric material means its a vulnerable area
special requirements
conductive threads
stretchable ink with minimum cracking
interconnection
connecting printed materials with something else
system integration of batteries and chips
interconnection materials
solder (melting alloy like tin) 217-240 C
conductive adhesive (metal particles inside, like copper tape)
printed conductive binding
conductive adhesives
-part of interconnection
epoxy (conductive paste and material to trigger polymerization)
isotropic conductive adhesives (conductive filler in all different directions)
anisotropic conductive adhesive paste (more resistance)
flat electric connectors
connect traces to outside controller and power source
-crimps or housing (conjoin metal)
zif connector: zero insertion force
lif connector-low insertion force
proximity sensor
if you are around something will happen
arduino board
-microcontroller board
Arduino board designs use a variety of microprocessors and controllers. The boards are equipped with sets of digital and analog input/output (I/O) pins that may be interfaced to various expansion boards (shields) and other circuits.
pins on arduino
places where you connect wires to construct a circuit
gnd: grounds the circuit
5V 3V: the voltage of power
analog: A0-A5-read signals from sensor
has digital pins too (digital: high or low, off or on like a switch, input and output)
(analog: gives a range
Use percolation theory to briefly explain why is the conductivity of a printed silver ink film more conductive after it is cured (dried).
After the ink film is cured, solvent and materials other than silver flakes are removed. The silver flakes has better chance to contact one another, therefore creates a path for the electrons to go through and improve the conductivity.
Briefly explain why a smooth surface of plastic film is important for printing conductive ink on it.
When a thin layer of ink printed on an uneven surface, the peaks may cause pinholes on a printed film. These pinholes showed up on a conductive ink film will impact the conductivity of the ink. And the valleys of the plastic film may also cause the ink to
List a few benefits of using paper as a substrate for flexible electronics. Do not copy the ones already listed in the ppt slides.
Paper is flexible, foldable, biodegradable, low cost, and people have more experience with paper products that can be easily adapted to different uses.
This image shows the stain of a flexible substrate used for building electronics. The original length of the substrate is L. How to describe the tensile strain which occurred at the outside of the substrate while bending, and the compressive strain occurr
Strain is defined as Delta L over L. The mechanical neutral plane does not change in dimension while being bent. Outside of the material is stretched, delta L is the length after elongated minus the original length. The strain is delta L over L. In this c
What type of common polymer film has the highest Tm that can be used for flexible and printed electronics?
PEN has higher Tm, PI or Polyimide has higher Tg, which is more practical for flexible electronics.
three categories of polymer film
semi crystalline (rigidity, ordered, pattern_
amorphous (have flexibility and elasticity)
amorphous solvent cast
sensor types
proximity
motion
temp
sound
chemical
capacitor
two electrodes
one insulator-dielectric
*can be in a circuit
capacitance
-The measure of the amount of charge that a capacitor can hold at a given voltage
-measured in farad (f)
-factors: surface area, distance, dielectric constant
c= EA/D
c=capitance
E= electric energy of dielectric
A= overlapping area of plates
D=distance be
dielectric constant
the measure of a materials influence on the electric field
dielectric strength
the maximum electric field of that material can endure without breakdown aka breakdown voltage
capacitive sensor
A capacitive sensor converts a change in position, or properties of the dielectric material into electrical signal
proximity sensing
A proximity sensing is a transducer that is able to detect the presence of nearby objects without any physical contact
key of capacitative sensing
accurate measurement of capacitance
RC circuit
Walmart tags
-have RFID which scans item into inventory
-fully printed (more cost effective)
the key element
the chip/brain
key of processing
transistors
transistors are and consist of
-semi-conductor device
gate
dielectric
semi-conductor
substrate
obstacles
-finding the right materials, not too rough
-develop better printed products NOT traditional print (aka additive manufacturing)
-subtractive is etching (lots of chemicals and waste)
picture of metal lines and chip
-transistor- covered in clear silicone protector
-the lines are charging
-the yellow clear over is the insulator-underneath the antenna
flexible hybrid electronics
-electronics for human monitoring
-can stretch
what do we need to make things work
CONNECTIVITY
bluetooth, wifi nfc
SENSING
POWER
-batteries, charging
modules are
building blocks
the main goal *
printing conductive materials on flexible materials
what is the ideal substrate
-flexible and lightweight most desired
polymer substrates
+: inexpensive, flexible
-: low thermal/mechanical stability, will melt
polymer film categories
pre-stabilized film: controlling heating and cooling to rearrange polymer chains
-semi crystalline-PET, PEN
amorphous-PC
amorphous solvent cast-PI
polymers
are chain like molecules with repeating structures (monomer isn't connected)
polymer morphology
the molecular arrangement
amorphous-very stable, doesn't change with heat (looks all jumbled, polyimide)
semi-crystalline-patterned, sharp melting points
tg and tm
glass transition temperature-softens/gooey
melting temperature
youngs modulus
measures force per unit area that is needed to stretch or compress a material sampleIt defines the relationship between stress (force per unit area) and strain (proportional deformation) in a material.
nm/2 or psi
tension modulus/modulus of elasticity
describes stress/strain relationships
stress/strain
coefficient of thermal expansion
-change in length per unit length of material per degree of temp. change
mechanical stability
high youngs modulus
low cte
residual stress
frozen in stress
-flow induced
-molding polymer parts
-thermal induced (cooling to form parts)
permeability
important parameter for OLED, photo voltaic devices
permeability rate: the rate at which a gas or vapor passes through a polymer
-want semi crystalline over amorphous
-can improve resistance with barrier
-PET and PEN (polyethylene, high permeability, SEMI
PET and PEN
PET: packaging
PEN: not clear, hazy, high tm high glass transition
high permeability: need to protect against oxygen and h2o
standard packaging film vs electronic grade film
standard: rough, bad, spiky
electronics: smooth, needs to be clean of dust
laminating dupont film: middle, flat but bumpy
metal substrates
-rare, flexible, good heat resistance, conductive
high young modulus, COSTLY
paper substrates
+: low cost, disposable, low thermal expansion
NEEDS SURFACE TREATMENT to reduce absorbency
-low end products: simple circuits, disposable sensors
biggest challenge
-surface roughness, porosity (can be improved by coating and calendaring)
dimensional stability (paper substrates)
-degree to which substrate maintains dimensions when subjected to change
-needed for registration accuracy
mechanical flexibility: no cracking when being folded
-special formulated papers-coating fibers
photo- more cracks, traces broken
pulp-less cracking
glass substrates
-best transparency
-low haze
-very smooth
-high process temperature
-high dimensional stability
-impermeable against oxygen and h2o
-scratch resistance
-insulator
-:fragile, heavy weight, costly, NOT AS FLEXIBLE
TPU
thermoplastic polyurethane
tm 160-190
carrier for flexible, stretchable wearble electronics
-adhesive
print materials
-printing or painting, works for either
-liquid or paste form necessary
-needs to maintain functionality
conductors
printed conductor- most common
thick film electronics-printed circuit boards
-silver flakes mixed with binder
-form percolated network
-lower conductivity than metal
conductive materials at nano scale
-incapsulated in organic ligand
-particles require sin
printed with silver flakes
for larger format prints
-not super efficient or high quality
-flakes stack which make the percolated network
functional materials
conductors
-metal, transparent (polymer(nano-wire) or inorganic), carbon
semi conductors
dielectrics
other
film vs flakes
film has higher conductivity than flakes
so does nano materials
Silver flakes are used for printing conductive traces.
nano materials
gold, silver and copper
-CAN be formulated into conductive inks
transparent conductors
touch screens
- polymer based
PEDOT:PSS (mixture of two inomers, conductive polymer) : poor performance, less transparent
PEDOT:PSS is polymer-based conductor. It is often used as transparent conductor to replace ITO. ITO has limited supply and also less
carbon based
cheaper!
graphene
-thinnest form of carbon
-transparent and strong
-excellent conductivity
-cheaper than AG
-difficult to form inks with
carbon
graphite
-good conductor, very stable
Graphene has higher conductivity than graphite, because of the sheet stru
metallic nano particles
-different shapes of nanoparticles
nano wires
metallic
-one dimensional
-used for transparent conductor
-difficult to print-coat the surface, can etch
bond together on cross pathways
basic mechanism
conductive inks require pathways for electrons to transfer
-printed conductive inks rely on contact between conductive materials
percolation threshold
critical point of volume fraction which can create continuous pathways for electrons to transfer
theory: need enough particles for path for electrons to go through, cure, solvents evaporate, particles in contact, close & strong
measuring conductivity
ohms= resistance
measured by multimeter
MEASUREMENT RELEVANT TO DISTANCE
bigger resistance-less conductivity
measuring sheet resistance
ohm/square
four point probe
dimensionless, doesn't matter what is squared
semi conductors
-either conductive or insulating
-organice based-n type or p type
usually air stabled n type
inorganic-not air stable, saline
conductive oxide- stable in air
non conductive materials
aka insulators
-keep wires separated in multi layer structure
-don't want to put more wires over it or you will short it
DO NOT connect the dielectric and insulator
if silver and carbon overlap, you will short circuit
breakdown voltage (non cond. continued)
-too much power, air is non conductive, break down the air and it becomes conductive
low breakdown voltage: concern of thin layers of dielectric material
HOMOGENOUS layer is important
any divet or crack in dielectric material means its a vulnerable area
special requirements
conductive threads
stretchable ink with minimum cracking
interconnection
connecting printed materials with something else
system integration of batteries and chips
interconnection materials
solder (melting alloy like tin) 217-240 C
conductive adhesive (metal particles inside, like copper tape)
printed conductive binding
conductive adhesives
-part of interconnection
epoxy (conductive paste and material to trigger polymerization)
isotropic conductive adhesives (conductive filler in all different directions)
anisotropic conductive adhesive paste (more resistance)
flat electric connectors
connect traces to outside controller and power source
-crimps or housing (conjoin metal)
zif connector: zero insertion force
lif connector-low insertion force
proximity sensor
if you are around something will happen
arduino board
-microcontroller board
Arduino board designs use a variety of microprocessors and controllers. The boards are equipped with sets of digital and analog input/output (I/O) pins that may be interfaced to various expansion boards (shields) and other circuits.
pins on arduino
places where you connect wires to construct a circuit
gnd: grounds the circuit
5V 3V: the voltage of power
analog: A0-A5-read signals from sensor
has digital pins too (digital: high or low, off or on like a switch, input and output)
(analog: gives a range
Use percolation theory to briefly explain why is the conductivity of a printed silver ink film more conductive after it is cured (dried).
After the ink film is cured, solvent and materials other than silver flakes are removed. The silver flakes has better chance to contact one another, therefore creates a path for the electrons to go through and improve the conductivity.
Briefly explain why a smooth surface of plastic film is important for printing conductive ink on it.
When a thin layer of ink printed on an uneven surface, the peaks may cause pinholes on a printed film. These pinholes showed up on a conductive ink film will impact the conductivity of the ink. And the valleys of the plastic film may also cause the ink to
List a few benefits of using paper as a substrate for flexible electronics. Do not copy the ones already listed in the ppt slides.
Paper is flexible, foldable, biodegradable, low cost, and people have more experience with paper products that can be easily adapted to different uses.
This image shows the stain of a flexible substrate used for building electronics. The original length of the substrate is L. How to describe the tensile strain which occurred at the outside of the substrate while bending, and the compressive strain occurr
Strain is defined as Delta L over L. The mechanical neutral plane does not change in dimension while being bent. Outside of the material is stretched, delta L is the length after elongated minus the original length. The strain is delta L over L. In this c
What type of common polymer film has the highest Tm that can be used for flexible and printed electronics?
PEN has higher Tm, PI or Polyimide has higher Tg, which is more practical for flexible electronics.
three categories of polymer film
semi crystalline (rigidity, ordered, pattern_
amorphous (have flexibility and elasticity)
amorphous solvent cast
sensor types
proximity
motion
temp
sound
chemical
capacitor
two electrodes
one insulator-dielectric
*can be in a circuit
capacitance
-The measure of the amount of charge that a capacitor can hold at a given voltage
-measured in farad (f)
-factors: surface area, distance, dielectric constant
c= EA/D
c=capitance
E= electric energy of dielectric
A= overlapping area of plates
D=distance be
dielectric constant
the measure of a materials influence on the electric field
dielectric strength
the maximum electric field of that material can endure without breakdown aka breakdown voltage
capacitive sensor
A capacitive sensor converts a change in position, or properties of the dielectric material into electrical signal
proximity sensing
A proximity sensing is a transducer that is able to detect the presence of nearby objects without any physical contact
key of capacitative sensing
accurate measurement of capacitance
RC circuit