Premium
Photothermally Responsive Inks for Inkjet‐Printing Secure Information
Author(s) -
Chirico Giuseppe,
Dacarro Giacomo,
O'Regan Colm,
Peltonen Jouko,
Sarfraz Jawad,
Taglietti Angelo,
Borzenkov Mykola,
Pallavicini Piersandro
Publication year - 2018
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.201800095
Subject(s) - photothermal therapy , inkwell , materials science , surface plasmon resonance , inkjet printing , absorption (acoustics) , optoelectronics , nanotechnology , irradiation , coating , optics , nanoparticle , composite material , physics , nuclear physics
2D patterns of photothermally responsive near‐infrared (NIR) absorbing gold nanostars (GNS), coated with multiple charged polymer layers, are inkjet‐printed on a glass surface. The shape of the localized surface plasmon resonance (LSPR) NIR absorption bands in the printed patterns loses its peaked form due to plasmon coupling, unless GNS are enveloped in multiple coating layers, keeping the inter‐GNS distance sufficiently large. In the latter case, the photothermal temperature increase (Δ T ) induced by the NIR laser irradiation follows a Δ T versus irradiation wavelength (λ irr ) profile with the same sharply peaked shape of the LSPR bands of the liquid ink. With this result, a new paradigm for inkjet‐writing secure information is introduced, as an alternative to the current methods based on direct visual inspection of printed patterns. While the printed ink patterns of GNS with different coatings are visually indistinguishable despite their different NIR absorption spectrum, their photothermal response changes dramatically with λ irr . This allows either to write and read simple information using a single λ irr (YES answer for Δ T > threshold) or to use multiple λ irr to write and read complex information like thermal bar codes and anti‐counterfeit signatures.