first question what is plasma if you
google plasma on the internet you'll
probably see this image right here these
are all the examples of both man-made
and plasmas found in nature doesn't
really tell you a whole lot about what
plasma actually is the nicest and
briefest description for me for plasma
is it's a gas that can conduct
electricity and that's it
that's what plasma is a gas that can
conduct electricity I think the the most
common plasma that you'll encounter and
everyday life is a fluorescent tube that
is a glow discharge one of the
byproducts of a plasma is the light that
it gives off so we use plasma to light
the darkness what we use at PBA Tecla is
the chemistry which is the byproduct of
the plasma that chemistry we use to
change properties of surfaces and we we
alter those properties to chain promote
adhesion
okay let's talk a little bit more about
plasma plasma you you'll hear as well is
the fourth state of matter if you add
energy to a solid eventually you'll
overcome some intermolecular forces you
get a liquid keep adding energy for
liquid you'll overcome more and make
your forces you get a gas keep adding
energy to a gas you'll eventually start
to break away some electrons from the
gas particles once these electrons break
away your gas suddenly becomes
conductive you've got a plasma that's
the fourth state of matter okay this is
really what we do at PVA tableau we
alter the surface chemistry of materials
using plasma so I want to talk a little
bit about an surface chemistry on this
slide right here this is everything that
plasma can do to modify your surface is
all on this slide so these five points
surf is etching which includes surface
cleaning plasma surface activation or
passivation this is really raising
surface energy or reducing the surface
energy plasma deposition of different
polymers like silicon dioxide or Teflon
or diamond like coatings this fourth one
is a little bit more complex and this
fourth one is really chemical grafting
this is grafting different functional
chemistry's to your surface like primary
amine groups or carboxylic groups etc
and finally reduction reduction off for
example metal oxides so I'm going to
talk about each one of these different
applications for plasma okay this is the
surf point the first one surface edging
there's two ways that plasma can etch
your surface at your clean a surface the
first is a chemical edge this is where
we will
react plasma particles with the surface
to form new volatile compounds that can
be removed by the pump if you're using a
low pressure plasma the other method is
the physical edge this is where we will
accelerate particles towards the surface
and they will act as a ballistic effect
and physically knock particles off your
surface so those are the two main
mechanisms for surface edging or surface
clean surface activation or passivation
this is where we raise the surface
energy or we reduce the surface energy
of a material raising the surface energy
this is where we make energy available
to to bond with an adhesive or an ink at
surface passivation this is where we
make the the surface inert one of the
ways that we can do that for example is
by adding fluorine groups or or coating
with a Teflon life coating that brings
me on to this light slide surface
coating there's a number of different
things that we can do with surface
coatings we can either deposit
functional clothings or chemical
coatings now this really is a plasma
enhanced chemical vapour deposition or
PE CVD process the functional coatings
you can see here they range from PTFE
quartz-like coatings diamond-like we can
deposit polyethylene glycols or
polyethylene oxide like coatings using
pecvd and also hydroxy ethyl
methacrylate
we can also deposit coatings that
contain a chemical functionality so
let's say you need a surface that has a
primary aiming functionality or an epoxy
group and we can do that using this
process a PECVD like process here this
is just to give you an example of an
untreated plasma surface if you're
trying to deposit the coating without
first treating the surface you can be
sure that there's going to be
contamination on the surface of your
product the second thing is there's no
because there's no chemistry on the
surface there's no way of predicting how
your functional molecule or biomolecule
or whatever coating you're trying to get
down in surface there's no way of
predicting how it's going to bind it
might bind active and down in which case
you've lost your functionality so the
first thing that plasma will do it
removes the contamination it cleans your
surface it normalizes your surface the
second step that plasma can do is
actually put down to pick two them here
is purple cups but it can deposit a
specific chemical functional group like
I mentioned before a primary amine or
carboxylic acid or an epoxy I'd
something like that so then when you do
expose it to your functional molecule
let's say if it's alda my terminator
carboxylic termini that and these are
primary amines you know it's going to go
aldehyde and down and then oxide
reduction just what the picture tells
you it's removing the oxide from the
metal I wish we could do it as good as
this but
these are XPS graphs of this is copper
and this is nickel basically what we're
showing you here is that as a function
of time we can increase the signal thank
pure copper and reduce the signal from
the various different couple of copper
oxides on the surface this is using
hydrogen based chemistry's we're looking
here at nickel nickel is sort of an odd
one you do see an increase an initial
increase in the nickel oxide
concentration followed by a sharp
reduction it does take a little bit
longer but we can do it we have
demonstrated that we can reduce nickel
oxides as well ok let's talk a little
bit about the chemical functionalities
that we're able to get down surfaces you
can see them across the top here a means
hydroxyl groups carboxyls aldehydes
Epoque sides and sulfide roles and I
went to the literature and I found all
of these different types of biomaterials
that were deposited on the surface using
these functionalities so for example
there there's a lot of publications on
the adsorption of cells to surfaces
they're using aiming groups in
particular but also hydroxyl and
carboxyls oligonucleotides and DNA's and
and proteins and enzymes lot of papers
using a pop side functionalities okay
there are two main ways of plasma
treating a surface trying to chemically
functionalize the surface the first is
is a straight activation process and the
second is what we call plasma
polymerization process this is by far
the better method a plasma activation
let's say you're looking for a primary
aiming group so you feed ammonia gas
into your chamber you look at about 2%
primary aiming on your surface using
ammonia gas
on the other hand if you feed in some
monomer species that you can Plumer eyes
on the surface that contains that
functional group for example an al
al-amin you will get in excess of 10%
primary aiming group on the surface so
it's a lot easier to control the
chemistry if you use this method here
but both methods are possible okay
let's then talk a little bit about some
of the applications a lot of the
applications that come through our
facility is for cleaning precision
cleaning of parts and again and we
talked about it in the introduction
there are two ways to clean the surface
let's say if you have a hydrocarbon
contaminant on your surface and you want
to remove it probably the best precursor
gas would be oxygen so you feed oxygen
into your chamber you activate it with
the plasma this oxygen will convert that
organic contaminants into co2 and water
the exact same combustion process as
what happens when you burn gasoline in
your car though those are the products
that are going at your pump the other
method is physical method let's say you
had an inorganic compound that's very
difficult to remove by converting it
into some kind of volatile chemical you
have to remove it physically by
accelerating ions towards the surface
and more or less sputtering them off
this slide just shows you some of the
examples of materials that we have we
can remove from surfaces machining oils
mold release agents polymer bleeds drill
smear carbon ash fingerprints etc etc
this is an interesting one here proteins
DNA in carbohydrates unfortunately we
can't call ourselves a sterilization
technique but plasma does sterilize it
sterilizes am a lot better than hydrogen
peroxide because not only do you get
your six log kill but you also remove
the debris that's left behind your
proteinaceous debris adhesion promotion
it's actually four ways that we can
promote the adhesion of them either an
ink or an adhesive or some sort of a
coating that you're trying to deposit on
the surface the first thing that we
talked about already the plasma will
clean the surface it will remove all the
contamination the second thing that it
can do is raise the surface energy it
can make energy available on the surface
to bond with your adhesive or your ink
or your clothing we can also roughen the
surface through bombardment now this
actually are the three bombardment we
can also use a chemical technique to
roughly the surface so of course the the
rougher your surface is now the more
surface area there is for binding to to
light
and finally chemical priming this we
talked about already so these are the
four ways that we can promote the
adhesion of either an inker and adhesive
or some sort of em a bio coating to your
surface this slide here just shows you
some of the improvements in adhesion
strength for different materials I can't
remember what the adhesive is to be
honest everything is in pounds per
square inch and this is the the gain
ratio so you know we're looking at you
know six times improvement for
polyamides 24 times improvements for
poly cell phones PTFE we've got 50 plus
times actually that's a polyethylene
texture
PTFE we can do the standard method for
activating PTFE towards adhesion
promotion is to use an ammonia plasma
the this is the result that you get with
an ammonia plasma you've also got a time
limit in which to do your downstream
processing the time limit is about a
half a day which is it's not very long
particularly if we're trying to
demonstrate what we can do and we've got
to send parts back in the post so we
developed a new method using an alcohol
plasma the adhesion strength improvement
is much better this graph here shows you
the contact angle over time we actually
pulled a part out of our lab that we did
a year ago we still have contact angle
of less than 20 degrees from a starting
point of about 115 blue brushes coatings
so plasma will not actually deposit the
lubricious coating what what gas plasma
surface modification does is it preps
the surface so that you can adsorb your
lubricious coating to that surface this
is again an example I just pulled it out
of the literature it's an argon oxygen
plasma treatment of these IOL and
intraocular lens delivery devices they
need to put their low pressures coating
on these devices so that when they
squeeze the lens into the eye it goes in
easily and doesn't damage the lens
itself this is the technique that they
use so they needed to clean the surface
and activate it so that this lubricious
coating would adhere and would not come
off when the lens was injected through
the cartridge hydrophilic surfaces the
exact same principle plasma can be used
to make surfaces permanently hydrophilic
or we can activate a surface so we can
deposit another coating that has has
hydrophilic properties some examples
here these are well plates
there are 384 well plates we what we we
have here is a bubble this bubble formed
because the surface of this polymer is
hydrophobic
after plasma treatment you never get
bubbles when you dispense a fluid into
these welds for the activation of tissue
culture media we were able to improve
the adhesion properties of cells the
substrates
we no longer found areas where there
were no cell attachment and we reduce
the amount of plumping that we observed
without
plasma surface treatment with plasma
surface treatment yeah we've got nice
uniform adhesion of cells anti-boy of
fouling coatings again it's the same
principle and we use plasma to
chemically functionalize the surface so
that when you expose it to your
functional coating for example an anti
biofouling coating that that coating
will adhere to the surface in this
particular example this is a peg chain
it's aldehyde terminated
the surface was
chemically grafted with primary amine
groups now if we got a low density of
primary amine groups on the surface when
we expose it to the the PEG chain the
concentration of the peg was not high
enough so when it was hydrated
it formed this kind of a spiral which
left access to contaminants or proteins
or microbes to actually reach the
surface we get a high enough density on
the surface this doesn't happen when you
hydrate the PEG chain it in tangles with
each other forming a nice nice barrier
right here antimicrobial coatings same
principle again this is just posed from
the literature that they were required a
primary aiming functionality and the
glutaraldehyde linker to put down the
round to microbial coating these are
just examples there's an a thousand and
one ways to skin this cat antithrombin
Janak coatings again in this case they
were looking for carboxylic acid
functionality on the surface
tissue engineering this is an emerging
area these tissue scaffolds are often
poly lactic acids or poly glycolic acids
to promote the adhesion particularly for
these porous type scaffolds they use
ammonia plasma cells don't seem to mind
whether it's a primary amine or a
secondary amine so in this case using a
plasma polymer is not critical doing a
straight ammonia plasma activation seems
to work very very well when we compared
this technique with a wet chemical
activation using ethanol for the the the
tightly poured scaffolds we were getting
about 80% cell seeding efficiency
whereas with the ammonia plasma
treatment we were still in excess of 99
percent cells eating efficiency drug
delivery coatings okay there there are
two there are two types of drug delivery
coving one is a coating that goes on top
of an antibiotic and allows the drug to
slowly release into the surroundings the
second one is for the like sulfur and in
inhaler devices where you're trying to
meter the amount of drug that goes into
the inhaler or that that's carried by
the propellant in this case we do a
Teflon coating to prevent the drug from
adhering to the inner walls of the
metering chamber
this is the drug release coving it's a
plasma deposit deposit it's poly and
butyl methacrylate after direct
deposition of this polymer we get kind
of a bi phase of illusion of the drug
if you oxygen plasma treat this clothing
kind of cross-linked the surface
afterwards you get a nice unifies
release over 40 days friction reduction
or or surface tack reduction we can
actually reduce the surface tack of
materials like nitrile rubber Zoar
silicone rubbers or AK relates using
plasma there's a number of different
ways of doing it we can either use them
fluorination technique or we can deposit
coatings and there are other
cross-linking methods that we can also
use by bombarding inert gases onto the
surface that reduces this tacky nature
the again we're comparing the reduction
of the coefficient of friction using
plasma we're comparing it to other
methods like fluorine ion implantation
fluorine gas treatment this is the
plasma right here we get the lowest main
coefficient of friction after plasma
treatment and the lower standard DVD
standard deviations
there's an interesting slide actually
this is an an SEM of nitrile rubber you
can see the mold lines of this it was an
o-ring
that we we use for this experiment these
are the molding lines that we observe
using SEM after plasma these molding
lines had completely disappeared and yet
we were not itching this surface at all
so we did some extended plasma processes
to see what the etching rate was because
when we saw this we thought we were
actually etching the material it turns
out we weren't so we're hypothesizing as
to how plasma works what we think is
happening is plasma is breaking or
breaking and activating these long
chains at the edges or sharp corners
they're kind of folding down and
reabsorbing to the surface is what we
think is happening okay I'm just going
to run through these slides very quickly
since I'm running out of time
these are just some of the applications
by market we've already mentioned assays
with chemical assays Culture Media micro
arrays we treat consumables of archery
consumables like for example reservoirs
for maximizing the recovery of reagents
at the bottom of these reservoirs we
activate these needle hubs prior to
adhesively bonding and potting these
needles to the polymer hub in
orthopaedics we it's mostly cleaning
after polishing of these hips dams that
chemical polishing we got to remove
a Polish that's done using plasma also
for peak implant implants for spinal
fusion cages etc we've clean those peak
parts and activate them as well toward
cell adhesion in ophthalmic s-- we make
these silicone hydrogel hydrophilic so
that the tear wets across the the
contact lens and it doesn't irritate the
eye we also do some work in the field of
inter ocular devices removing the
surface tack from the haptics for
example so that they unfold readily once
they're inserted into the eye wounds
treatment we can treat fabrics as well
with plasma and finally filter membranes
we can treat filter membranes to improve
the hydrophilicity and improved
wettability i'll take any questions and
if anybody wants to find out more about
plasma we're in booth three two three
one