Research Information System
16th NANOSCIENCE & NANOTECHNOLOGY CONFERENCE, Ankara, Turkey, 5 - 08 September 2022, pp.375
In today's world, counterfeiting is a major problem.
Increasing counterfiting cause economic loss, health risks, and social issues.
For this reason, academic and industrial circles have focused on the
development of new generation of security labels/barcodes to provide effective
anticounterfeiting measures. Physical encoding systems called “physically
unclonable functions” (PUFs) have attracted great attention in last decade, due
to the potential to provide unique encoding for each object/application that
even the manufacturers cannot repeat thanks to randomness of process.
Therefore, in order to use this advantage of PUFs effectively, it is essential
to develop multiplexed PUFs fabricated by versatile and cost effective
fabrication techniques. In this study, an unique approach that reinforces the
advantages of PUFs with a versatile fabrication method is presented. Ourapproach
is based on the practical fabrication of patterns consisting of polymeric
features deposited at spatially random positions
using the electrospraying. Here, electrohydrodynamic instabilities during
electrospraying provide the formation of completely random and complex
polymeric structures. The additive nature of the process enables sequential
deposition of multiple materials on the same substrate. Furthermore, the
solution processing-based fabrication allows incorporation of functional
materials into polymeric features and enables the formation of additional
security layers. By taking advantage of the advantages mentioned earlier and
enriching the technique, multicolor PUFs with multi-layered security measures
have been fabricated. Specifically, PUFs containing layered security measures
from many different polymer systems such as polystyrene, polymethyl
methacrylate, polyethylene oxide, and polyvinylpyrrolidone have been produced
and their practical applications have been demonstrated. Furthermore, systematic
examination of the process parameters, the condition-structure relationship was
revealed where electrosprayed PUF structures display a wide variety of distinct
morphologies as well as extend in range from micro to nanoscale. It is
demonstrated that security keys extracted from the response of the resulting features
exhibit close to ideal values when tested for quantitative metrics (randomness,
uniqueness, uniformity, reliability) that are widely used for assessing PUF
performance. Electrosprayed PUFs, which stand out with their performance and characteristics,
can be taken further and cooperated with fluorescent molecules directly during
the process. The resulting multicolor PUFs can be authenticated at different
levels, which can be performed independently. Here, the random distribution of
features forms the first level of security, which can be verified by
conventional optical microscopy imaging, and unique morphology of features
forms the second security layer, which can be authenticated by advanced
techniques (SEM, AFM, etc.), and lastly, the multiple responses from unique
fluorescence from randomly located photoluminescent molecules form a third
layer of security that can be authenticated with fluorescence imaging.
Finallly, the high coding capacity was determined and the impenetrable layers
of security defined procedurally, and the multicolor PUFs are applied directly
as security label on the goods. The images taken from the application/good to
be authenticated are verified by comparing the keys obtained with the
binaryization and subsequent 256-bit code extraction procedures with those in
the database. In addition to this common authentication method, much more
practical and faster authentication mechanisms have been developed within the
scope of our study, where many limitations are eliminated thanks to the direct
implantation of image feature matching algorithms into PUF applications.