Browsing by Subject "Physically unclonable functions"

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Open Access
Organic light-emitting physically unclonable functions
(Wiley-VCH Verlag GmbH & Co. KGaA, 2021-12-22) Kayacı, N.; Özdemir, R.; Kalay, M.; Kiremitler, N. B.; Usta, H.; Önses, Mustafa Serdar
The development of novel physically unclonable functions (PUFs) is of growing interest and fluorescent organic semiconductors (f-OSCs) offer unique advantages of structural versatility, solution-processability, ease of processing, and great tuning ability of their physicochemical/optoelectronic/spectroscopic properties. The design and ambient atmosphere facile fabrication of a unique organic light-emitting physically unclonable function (OLE-PUF) based on a green-emissive fluorescent oligo(p-phenyleneethynylene) molecule is reported. The OLE-PUFs have been prepared by one-step, brief (5 min) thermal annealing of spin-coated nanoscopic films (≈40 nm) at a modest temperature (170 °C), which results in efficient surface dewetting to form randomly positioned/sized hemispherical features with bright fluorescence. The random positioning of molecular domains generated the unclonable surface with excellent uniformity (0.50), uniqueness (0.49), and randomness (p > 0.01); whereas the distinctive photophysical and structural properties of the molecule created the additional security layers (fluorescence profile, excited-state decay dynamics, Raman mapping/spectrum, and infrared spectrum) for multiplex encoding. The OLE-PUFs on substrates of varying chemical structures, surface energies and flexibility, and direct deposition on goods via drop-casting are demonstrated. The OLE-PUFs immersed in water, exposed to mechanical abrasion, and read-out repeatedly via fluorescence imaging showed great stability. These findings clearly demonstrate that rationally engineered solution-processable f-OSCs have a great potential to become a key player in the development of new-generation PUFs.
Open Access
Physically unclonable surfaces via dewetting of polymer thin films
(American Chemical Society, 2021-03-10) Torun, N.; Torun, İ.; Şakir, M.; Kalay, M.; Önses, Mustafa Serdar
From anti-counterfeiting to biotechnology applications, there is a strong demand for encoded surfaces with multiple security layers that are prepared by stochastic processes and are adaptable to deterministic fabrication approaches. Here, we present dewetting instabilities in nanoscopic (thickness <100 nm) polymer films as a form of physically unclonable function (PUF). The inherent randomness involved in the dewetting process presents a highly suitable platform for fabricating unclonable surfaces. The thermal annealing-induced dewetting of poly(2-vinyl pyridine) (P2VP) on polystyrene-grafted substrates enables fabrication of randomly positioned functional features that are separated at a microscopic length scale, a requirement set by optical authentication systems. At a first level, PUFs can be simply and readily verified via reflection of visible light. Area-specific electrostatic interactions between P2VP and citrate-stabilized gold nanoparticles allow for fabrication of plasmonic PUFs. The strong surface-enhanced Raman scattering by plasmonic nanoparticles together with incorporation of taggants facilitates a molecular vibration-based security layer. The patterning of P2VP films presents opportunities for fabricating hybrid security labels, which can be resolved through both stochastic and deterministic pathways. The adaptability to a broad range of nanoscale materials, simplicity, versatility, compatibility with conventional fabrication approaches, and high levels of stability offer key opportunities in encoding applications.
Embargo
Structurally colored physically unclonable functions with ultra-rich and stable encoding capacity
(Wiley-VCH Verlag GmbH & Co. KGaA, 2024-12-10) Esidir, A.; Ren, Mn.; Pekdemir S.; Kalay, M.; Kayacı, N.; Günaltay, N.; Usta, H.; Xuang, X.; Önses, Mustafa Serdar
Identity security and counterfeiting assume a critical importance in the digitized world. An eﬀective approach to addressing these issues is the use of physically unclonable functions (PUFs). The overarching challenge is a simultaneous combination of extremely high encoding capacity, stable operation, practical fabrication, and a widely available readout mechanism. Herein this challenge is addressed by designing an optical PUF via exploiting the thickness-dependent structural color formation in nanoscopic ﬁlms of ZnO. The structural coloration ensures authentication using widely available bright-ﬁeld-based optical readout, whereas the metal oxide provides a high degree of structural stability. True physical randomness in spatial position is achieved by physical vapor deposition of ZnO through stencil masks that are fabricated by pore formation in polycarbonate membranes via photothermal processing of stochastically positioned plasmonic nanoparticles. Structural coloration emerges from thin ﬁlm interference as conﬁrmed via simulation studies. The rich color variation and stochastic deﬁnition of domain size and geometry result in chaotic features with an encoding capacity that approaches (6.4×105)(2752×2208) . Deep learning-based authentication is further demonstrated by transforming these chaotic features into unbreakable codes without ﬁeld limitations. This ultra-rich encoding capacity, coupled with outstanding thermal and chemical stability, forms a new cutting edge for state-of-the-art PUF-based encoding systems.