Browsing by Author "Torun, I."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Open Access pH tunable patterning of quantum dots(Wiley-VCH Verlag GmbH & Co. KGaA, 2023-09-01) Torun, I.; Huang, C.; Kalay, M.; Shim, M.; Önses, M. SerdarPatterning of quantum dots (QDs) is essential for many, especially high-tech, applications. Here, pH tunable assembly of QDs over functional patterns prepared by electrohydrodynamic jet printing of poly(2-vinylpyridine) is presented. The selective adsorption of QDs from water dispersions is mediated by the electrostatic interaction between the ligand composed of 3-mercaptopropionic acid and patterned poly(2-vinylpyridine). The pH of the dispersion provides tunability at two levels. First, the adsorption density of QDs and fluorescence from the patterns can be modulated for pH > approximate to 4. Second, patterned features show unique type of disintegration resulting in randomly positioned features within areas defined by the printing for pH <= approximate to 4. The first capability is useful for deterministic patterning of QDs, whereas the second one enables hierarchically structured encoding of information by generating stochastic features of QDs within areas defined by the printing. This second capability is exploited for generating addressable security labels based on unclonable features. Through image analysis and feature matching algorithms, it is demonstrated that such patterns are unclonable in nature and provide a suitable platform for anti-counterfeiting applications. Collectively, the presented approach not only enables effective patterning of QDs, but also establishes key guidelines for addressable assembly of colloidal nanomaterials.Item Open Access Robust superhydrophobic fabrics by infusing structured polydimethylsiloxane films(John Wiley & Sons, Inc., 2021-06-22) Celik, N.; Torun, I.; Ruzi, M.; Mustafa Serdar, ÖnsesSuperhydrophobic coatings have large application potential in self-cleaning textiles. Low durability, high cost of fabrication, and environmental concerns over the usage of chemicals such as fluorocarbons limit the utilization of superhydrophobic coatings. This study reports a convenient and inexpensive approach to fabricate robust and fluorine-free superhydrophobic fabrics based on the transfer of structured polymer films and hydrophobic nanoparticles. In this approach, polydimethylsiloxane (PDMS) is infused between sheets of fabric and paper, followed by curing and removal of the paper. This process results in a fabric infused with PDMS whose structure is a negative replica of the paper surface. Then, hydrophobic nanoparticles are sprayed onto the structured PDMS side of the fabric. The infusion of PDMS and subsequent deposition of the hydrophobic nanoparticles enables strong bonding, as shown by the excellent solvent stability of the superhydrophobic fabric under ultrasonication. The proposed approach is universal in that it can be applied to almost any textiles, which upon coating, exhibited superhydrophobicity with a water contact angle of 172° and a sliding angle of 3°. Furthermore, the superhydrophobic fabric showed robust durability against water spray impact and mechanical bending where it can keep superhydrophobicity for at least 200 cycles of each test.Item Open Access Tattoo-like multi-color physically unclonable functions(John Wiley and Sons Inc, 2023-12-07) Kiremitler, N. B.; Esidir, A.; Drake, G. A.; Yazıcı, A. F.; Şahin, F.; Torun, I.; Kalay, M.; Kelestemur, Y.; Demir, Hilmi Volkan; Shim, M.; Mutlugün, Evren; Önses, Mustafa SerdarAdvanced anti-counterfeiting and authentication approaches are in urgent need of the rapidly digitizing society. Physically unclonable functions (PUFs) attract significant attention as a new-generation security primitive. The challenge is design and generation of multi-color PUFs that can be universally applicable to objects of varied composition, geometry, and rigidity. Herein, tattoo-like multi-color fluorescent PUFs are proposed and demonstrated. Multi-channel optical responses are created by electrospraying of polymers that contain semiconductor nanocrystals with precisely defined photoluminescence. The universality of this approach enables the use of dot and dot-in-rod geometries with unique optical characteristics. The fabricated multi-color PUFs are then transferred to a target object by using a temporary tattoo approach. Digitized keys generated from the red, green and blue fluorescence channels facilitate large encoding capacity and rapid authentication. Feature matching algorithms complement the authentication by direct image comparison, effectively alleviating constraints associated with imaging conditions. The strategy that paves the way for the development of practical, cost-effective, and secure anticounterfeiting systems is presented.