Optical Trapping
The ability to manipulate and trap biological matter at the nanoscale is essential across a wide range of health applications, including single molecule biophysics, drug development, and cancer diagnostics. Optical trapping of biomolecules enables non-contact, high-precision manipulation of biological particles at the micro- and nanoscale [1].
Over the years, our research group has proposed and investigated several configurations for the optical trapping of single molecules. Among these, an inverted hybrid dielectric–plasmonic nanobowtie structure was demonstrated to trap single viruses with a diameter of 100 nm, achieving a stability greater than 10 and a stiffness of 2.203 fN/nm [2]. Similarly, a silicon-based dielectric nanobowtie dimer was developed for trapping of the same type of viruses, achieving a stability of 1, a stiffness of 0.33 fN/nm, and optical forces of approximately 27 fN at an input power of 6 mW/μm² [3]. Additionally, a hybrid photonic–plasmonic cavity, integrating a photonic crystal nanobeam with a plasmonic bowtie antenna, has been proposed by our research group for the efficient trapping of a single 200 nm gold nanoparticle. This configuration demonstrated a stable trapping duration exceeding 5 minutes with a low input power of 190 μW, an ultra-high Q/V ratio on the order of 10⁶ (λ/n) ³ [4]. To further enhance trapping performance at the nanoscale, a photonic–plasmonic cavity based on a 1D photonic crystal vertically coupled to a gold plasmonic structure has been designed. This configuration enables the trapping of a single nanoparticle with a diameter below 100 nm and features a Q-factor of 2.8 × 10³, a Q/V ratio of 7 × 10⁶(λ/n) ³, confirming its suitability for advanced biomedical applications such as proteomics and oncology [5]. To monitor the heterogeneity of biological systems and enable high-efficiency diagnostic testing, our research group experimentally demonstrated for the first time the multiplexed optical trapping of hundreds of 100 nm polystyrene beads over a 10 minute period, using a total input power of ~26 mW (∼7 μW per site), with strong energy confinement (Q ≈ 350, R = 0.8) [6]. Additionally, the trapping of lipid vesicles was achieved using a moderate optical intensity below 250 μW/μm². This result was obtained using a dielectric metasurface composed of nanocuboid arrays supporting a coupled anapole state, enabling large-scale, low-power trapping through high-Q, angle-tolerant resonances excited by a focused laser beam. The system operates over a 30 μm area, simultaneously activating thousands of trapping sites [6].
References
[1] C. Ciminelli, F. Dell’Olio, D. Conteduca, D. and M.N. Armenise, “Integrated Photonic and Plasmonic Resonant Devices for Label‐Free Biosensing and Trapping at the Nanoscale,” Physica Status Solidi A,16(3),1800561,2019. doi: https://doi.org/10.1002/pssa.201800561
[2] P. Colapietro, G. Brunetti, A. di Toma, F. Ferrara, M.S. Chiriacò and C. Ciminelli, “High Stability and Low Power Nanometric Bio-Objects Trapping through Dielectric–Plasmonic Hybrid Nanobowtie,” Biosensors, 14(8), 390, 2024. doi: https://doi.org/10.3390/bios14080390
[3] G. Brunetti, N. Sasanelli, M.N. Armenise and C. Ciminelli, “Nanoscale optical trapping by means of dielectric bowtie,” Photonics, 9(6), 424, 2022. doi: https://doi.org/10.3390/photonics9060425
[4] D. Conteduca, C. Reardon, M.G. Scullion, F. Dell’Olio, M.N. Armenise, T.F. Krauss and C. Ciminelli, “Ultra-high Q/V hybrid cavity for strong light-matter interaction,” APL Photonics,2, (8), 2017. doi: https://doi.org/10.1063/1.4994056
[5] C. Ciminelli, D. Conteduca, F. Dell’Olio, M.N. Armenise, “Design of an optical trapping device based on an ultra-high Q/V resonant structure,” IEEE Photonics J.,6 (6),1-16, 2014.doi: 10.1109/JPHOT.2014.2356496. Link: https://ieeexplore.ieee.org/abstract/document/6895109
[6] D. Conteduca, G. Brunetti, G. Pitruzzello, F. Tragni, K. Dholakia, T.F. Krauss and C. Ciminelli, “Exploring the limit of multiplexed near-field optical trapping,”Acs Photonics,8(7),2060-2066, 2021.doi: https://doi.org/10.1021/acsphotonics.1c00354
[7] D. Conteduca, G. Brunetti, I, Barth, S.D. Quinn, C. Ciminelli, and T.F. Krauss,” Multiplexed near-field optical trapping exploiting anapole states,” ACSnano,17(17),16695-167022, 2023.doi: https://pubs.acs.org/doi/10.1021/acsnano.3c03100.