polydimethylsiloxane
Polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone, is a silicone polymer with a wide variety of uses, from cosmetics to industrial lubrication and passive daytime radiative cooling.
PDMS is particularly known for its ...
(PDMS) matrix are broken to controlably etch PDMS (i.e. dissolve) at a slow rate along the outside of a PDMS channel formed with a patterned PDMS stamp applied to a surface. The channel in the stamp can be enlarged in the order of tens of
nanometers
330px, Different lengths as in respect to the molecular scale.
The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm), or nanometer (American and British English spelling differences#-r ...
to several
micrometre
The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...
s. Exposing a fresh area of a surface that can be reacted with.
Summary
PDMS contains polymer chains of silicon-oxygen bonds, these bonds can be broken by
fluoride
Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...
containing species, in the same way that silicon wafers are prepared by etching with
hydrofluoric acid
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colorless, acidic and highly corrosive. A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling p ...
,
ammonium fluoride
Ammonium fluoride is the inorganic compound with the formula NH4F. It crystallizes as small colourless prisms, having a sharp saline taste, and is highly soluble in water. Like all fluoride salts, it is moderately toxic in both acute and chronic o ...
and related compounds. By placing a PDMS stamp that contains a channel that can be externally filled on to a surface, that surface can be functionalised in the area of the channel. By then running an etching solution through the channel, part of the PDMS will be removed. Exposing a fresh area of the surface. This can then be functionaliesd by appropriate chemistry. The width of feature produced is controlled by etchant and time.
To apply this technique for the production of small patterned features it is necessary that the surface can be reacted to passivate it in the area exposed by the channel, followed by etching and then reacted in away that will only occur in the newly exposed area.
References
Perring M., Mitchell, M., Kenis P. J. A., Bowden N. B., ''Chem. Mat'' 2007 ''19''(11), 2903
Nanoelectronics