Fluorescence-specific Biocompatible Zinc Oxide Nanoparticles for Anticounterfeiting Ink and its Reagent Free Synthesis thereof
Technology Category/Market
Technology: Fluorescence-specific biocompatible zinc oxide nanoparticles for anticounterfeiting ink and its reagent free synthesis
Category: Micro & Nano Technologies
Industry: Printing, Consumer Goods & Electronics,Pharmaceuticals and Healthcare
Application: Security Inks, Authentication and Verification
Market: The global market size estimated to reach USD 4.71 billion by 2032, growing at a CAGR of 4.03% during the forecast period (2024–2032)
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Problem Statement
- Photoluminescence study is crucial for understanding luminescence properties of materials like ZnO.
- Control over near band-edge emission and deep-level emission is challenging in single-step synthesis processes.
- Anti-counterfeiting remains a significant challenge, necessitating new materials and technologies.
- Various organic and inorganic samples explored for creating fluorescent ink are mostly toxic.
- Unsaturated complex organic compounds are biocompatible but not stable or water-resistant.
- Researchers are aiming to synthesize biocompatible and cost-effective quantum dots (QDs) for fluorescent ink.
- ZnO is a biocompatible material highly fluorescent in UV-A and B light excitation.
- Fluorescent fiber is used in bank currency, passports, and stamps for anti-counterfeiting.
Technology
Method:
- ZnO powder is pelletized and sintered at 700-900°C for 22-26 hours to create strong, unbreakable ZnO pellets.
- Sintered ZnO pellets are immersed in ethanol, and femtosecond laser pulses are focused on them to ablate ZnO surface, and produce nanoparticles.
- The laser operates at 1 kHz repetition rate, with pulse width adjustable between 150-750 fs and ablation power 0.25-1.5 W, and is raster scanned for 15-25 minutes.
- The nanoparticles are ablated, then centrifuged at 4500-5500 rpm to ensure uniform particle size distribution, and the final nanoparticles are collected.
Key Features/Value Proposition
ZnO Nanoparticles’ Fluorescence-Specific Emission Profile
- Fluorescence emission only under UV excitation in 260-365 nm range.
- Sharp near band-edge emission at 378 nm.
- Broad green emission at 520 nm due to deep level emission (DLE).
- Useful for anti-counterfeiting applications due to UV- excitation.
- Blind to visible wavelengths, i.e. 400-700 nm
ZnO Nanoparticle Size and Distribution
- Average size: 4-5 nm, particle size distribution: 2 nm.
- Smaller sizes and modified surface properties improve fluorescence efficiency and stability .
- Similar size with different fluorescent properties are crucial for anti-counterfeiting inks application.
ZnO Nanoparticles’ Tunable Emission Profile
- Photoluminescence emission tunable between violet to green.
- Color adjustment based on DLE to NBE emission ratio.
- Enhances ink versatility for various security applications.
Reagent-Free and One-Step Synthesis of ZnO Nanoparticles
- Utilizes femtosecond laser ablation in liquid (fs-PLAL) method for synthesis.
- Process includes pelletizing ZnO powder, sintering at 700-900°C for 22-26 hours, laser ablation in a solvent, and centrifuging for uniform particle size distribution.
- This reagent-free method simplifies production, reduces costs, and minimizes environmental impact.
ZnO Nanoparticles’ Deep Level Emission Control (Green emission)
- Adjust pulse duration and ablation power during synthesis.
- Enhance DLE emission by varying laser ablation power from 0.5 W to 1.5 W.
- Maintain pulse duration between 500-600 fs.
- Fine-tune green emission for anti-counterfeiting ink fluorescence characteristics.
ZnO Nanoparticles as Fluorescent Anti-Counterfeiting Ink
- No additional binders or additives needed. Simple, cost-effective process.
- Ideal for currency, documents, products. Offers hidden security under UV light.
Questions about this Technology?
Contact for Licensing
Research Lab
Prof. Sivarama KrishnanÂ
Prof. Ramachandra Rao M S
Department of Physics
Intellectual Property
IITM IDF Ref. 2761
Patent No: IN 550055
Technology Readiness Level
TRL- 3
Experimentally Proof of concept