The counterfeiting of goods has important economic implications and is also a threat to health and security. Incorporating anti-counterfeiting tags with physical unclonable functions (PUFs) into products is a promising solution for their authentication. PUFs are unique random physical patterns of taggants that cannot be copied and must be fabricated by a stochastic process that affords a large number of robust PUF tags. A PUF tag has a physical pattern that, if read with an appropriate analytical tool, can be recorded and stored. The PUF tag is then the ‘key’, whereas the stored pattern is the ‘lock’. This combination forms PUF keys that provide unbreakable encryption and combat counterfeiting. The stochastic assembly of physical patterns made from taggants exhibiting particular molecular properties is thus an excellent approach to designing new PUF keys. The counterfeiting of goods has economic implications and is a threat to health and security. One promising solution for product authentication is the incorporation of physical unclonable functions. This Review delineates how stochastic chemical processes can afford unique anti-counterfeiting tags that cannot be reproduced.

Physical unclonable functions generated through chemical methods for anti-counterfeiting

Optical nanomaterials have been widely used in anticounterfeiting applications. There have been significant developments powered by recent advances in material science, printing technologies, and the availability of smartphone-based decoding technology. Recent progress in this field is surveyed, including the availability of optical reflection, absorption, scattering, and luminescent nanoparticles. It is demonstrated that advances in the design and synthesis of lanthanide-doped upconversion nanoparticles will lead to the next generation of anticounterfeiting technologies. Their tunable optical properties and optical responses to a range of external stimuli allow high-security level information encoding. Challenges in the scale-up synthesis of nanomaterials, engineering of assessorial devices for smart-phone-based decryption, and alignment to the potential markets which will lead to new directions for research, are discussed.

Optical Nanomaterials and Enabling Technologies for High-Security-Level Anticounterfeiting.

An ideal anti-counterfeiting technique has to be inexpensive, mass-producible, nondestructive, unclonable and convenient for authentication. Although many anti-counterfeiting technologies have been developed, very few of them fulfill all the above requirements. Here we report a non-destructive, inkjet-printable, artificial intelligence (AI)-decodable and unclonable security label. The stochastic pinning points at the three-phase contact line of the ink droplets is crucial for the successful inkjet printing of the unclonable security labels. Upon the solvent evaporation, the three-phase contact lines are pinned around the pinning points, where the quantum dots in the ink droplets deposited on, forming physically unclonable flower-like patterns. By utilizing the RGB emission quantum dots, full-color fluorescence security labels can be produced. A convenient and reliable AI-based authentication strategy is developed, allowing for the fast authentication of the covert, unclonable flower-like dot patterns with different sharpness, brightness, rotations, amplifications and the mixture of these parameters.

Inkjet-printed unclonable quantum dot fluorescent anti-counterfeiting labels with artificial intelligence authentication.

The rapid growth of research in the areas of chemical and biochemical sensors, lab-on-a-chip, mobile technology, and wearable electronics offers an unprecedented opportunity in the development of mobile and wearable point-of-care testing (POCT) systems for self-testing. Successful implementation of such POCT technologies leads to minimal user intervention during operation to reduce user errors; user-friendly, easy-to-use and simple detection platforms; high diagnostic sensitivity and specificity; immediate clinical assessment; and low manufacturing and consumables costs. In this review, we discuss recent developments in the field of highly integrated mobile and wearable POCT systems. In particular, aspects of sample handling platforms, recognition elements and sensing methods, and new materials for signal transducers and powering devices for integration into mobile or wearable POCT systems will be highlighted. We also summarize current challenges and future prospects for providing personal healthcare with sample-in result-out mobile and wearable POCT.

Recent progress, challenges, and prospects of fully integrated mobile and wearable point-of-care testing systems for self-testing

Heart failure (HF) is the end-stage of cardiovascular diseases, which is associated with a high mortality rate and high readmission rate. Household early diagnosis and real-time prognosis of HF at bedside are of significant importance. Here, we developed a highly sensitive and quantitative household prognosis platform (termed as UC-LFS platform), integrating a smartphone-based reader with multiplexed upconversion fluorescent lateral flow strip (LFS). Dual-color core–shell upconversion nanoparticles (UCNPs) were synthesized as probes for simultaneously quantifying two target antigens associated with HF, i.e., brain natriuretic peptide (BNP) and suppression of tumorigenicity 2 (ST2). With the fluorescent LFS, we achieved the specific detection of BNP and ST2 antigens in spiked samples with detection limits of 5 pg/mL and 1 ng/mL, respectively, both of which are of one order lower than their clinical cutoff. Subsequently, a smartphone-based portable reader and an analysis app were developed, which could rapi...

Household Fluorescent Lateral Flow Strip Platform for Sensitive and Quantitative Prognosis of Heart Failure Using Dual-Color Upconversion Nanoparticles

Upconversion nanoparticles based FRET aptasensor for rapid and ultrasenstive bacteria detection

Medicine counterfeiting is a serious issue worldwide, involving potentially devastating health repercussions. Advanced anti-counterfeit technology for drugs has therefore aroused intensive interest. However, existing anti-counterfeit technologies are associated with drawbacks such as the high cost, complex fabrication process, sophisticated operation and incapability in authenticating drug ingredients. In this contribution, we developed a smart phone recognition based upconversion fluorescent three-dimensional (3D) quick response (QR) code for tracking and anti-counterfeiting of drugs. We firstly formulated three colored inks incorporating upconversion nanoparticles with RGB (i.e., red, green and blue) emission colors. Using a modified inkjet printer, we printed a series of colors by precisely regulating the overlap of these three inks. Meanwhile, we developed a multilayer printing and splitting technology, which significantly increases the information storage capacity per unit area. As an example, we directly printed the upconversion fluorescent 3D QR code on the surface of drug capsules. The 3D QR code consisted of three different color layers with each layer encoded by information of different aspects of the drug. A smart phone APP was designed to decode the multicolor 3D QR code, providing the authenticity and related information of drugs. The developed technology possesses merits in terms of low cost, ease of operation, high throughput and high information capacity, thus holds great potential for drug anti-counterfeiting.

Shurui Wang

Papers

Upconversion nanoparticles based FRET aptasensor for rapid and ultrasenstive bacteria detection

Household Fluorescent Lateral Flow Strip Platform for Sensitive and Quantitative Prognosis of Heart Failure Using Dual-Color Upconversion Nanoparticles

Three-dimensional quick response code based on inkjet printing of upconversion fluorescent nanoparticles for drug anti-counterfeiting

Labeling and long-term tracking of bone marrow mesenchymal stem cells in vitro using NaYF4:Yb(3+),Er(3+) upconversion nanoparticles.