Abstract:From physics to biology,
temperature is often a critical factor.
Most existing techniques (e.g., ovens, incubators, ...) only provide
global temperature control and incur strong inertia. Thermoplasmonic
heating is drawing increasing interest by giving access to fast, local,
and contactless optical temperature control. However, tailoring temperature
at the microscale is not straightforward since heat diffusion alters
temperature patterns. In this article, we propose and demonstrate
an accurate and reconfigurabl… Show more
“…1b ). The contribution from each of the AuNRs excited by the pump leads to a steady-state 3D temperature distribution that extends over the resonant illumination area 26 ; thereby enabling thermal landscape engineering by beam shaping 27 , 28 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Beyond the straightforward temperature landscape generated in this work, the colloidal-based plasmonic substrates open the possibility to further engineer the temperature field via beam-shaping 27 , 28 . This not only allows extensive reconfigurability of the temperature field in space and time, which leads to higher degree of control over the fluid and particle dynamics 15 , but also allows greater ease of fabrication compared to nanofabricated plasmonic structures 38 .…”
Using light to manipulate fluids has been a long-sought-after goal for lab-on-a-chip applications to address the size mismatch between bulky external fluid controllers and microfluidic devices. Yet, this goal has remained elusive due to the complexity of thermally driven fluid dynamic phenomena, and the lack of approaches that allow comprehensive multiscale and multiparameter studies. Here, we report an innovative optofluidic platform that fulfills this need by combining digital holographic microscopy with state-of-the-art thermoplasmonics, allowing us to identify the different contributions from thermophoresis, thermo-osmosis, convection, and radiation pressure. In our experiments, we demonstrate that a local thermal perturbation at the microscale can lead to mm-scale changes in both the particle and fluid dynamics, thus achieving long-range transport. Furthermore, thanks to a comprehensive parameter study involving sample geometry, temperature increase, light fluence, and size of the heat source, we showcase an integrated and reconfigurable all-optical control strategy for microfluidic devices, thereby opening new frontiers in fluid actuation technology.
“…1b ). The contribution from each of the AuNRs excited by the pump leads to a steady-state 3D temperature distribution that extends over the resonant illumination area 26 ; thereby enabling thermal landscape engineering by beam shaping 27 , 28 . Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Beyond the straightforward temperature landscape generated in this work, the colloidal-based plasmonic substrates open the possibility to further engineer the temperature field via beam-shaping 27 , 28 . This not only allows extensive reconfigurability of the temperature field in space and time, which leads to higher degree of control over the fluid and particle dynamics 15 , but also allows greater ease of fabrication compared to nanofabricated plasmonic structures 38 .…”
Using light to manipulate fluids has been a long-sought-after goal for lab-on-a-chip applications to address the size mismatch between bulky external fluid controllers and microfluidic devices. Yet, this goal has remained elusive due to the complexity of thermally driven fluid dynamic phenomena, and the lack of approaches that allow comprehensive multiscale and multiparameter studies. Here, we report an innovative optofluidic platform that fulfills this need by combining digital holographic microscopy with state-of-the-art thermoplasmonics, allowing us to identify the different contributions from thermophoresis, thermo-osmosis, convection, and radiation pressure. In our experiments, we demonstrate that a local thermal perturbation at the microscale can lead to mm-scale changes in both the particle and fluid dynamics, thus achieving long-range transport. Furthermore, thanks to a comprehensive parameter study involving sample geometry, temperature increase, light fluence, and size of the heat source, we showcase an integrated and reconfigurable all-optical control strategy for microfluidic devices, thereby opening new frontiers in fluid actuation technology.
“…Thermo-optic modulation is well established in guided wave optics via plasmonic modulators 22 , 23 and with active metasurfaces for infrared wavelengths 24 , 25 . It has been employed in combination with thermoplasmonic-base temperature control 26 to perform photothermal imaging 27 , measure temperature gradients 28 , 29 and shaping temperature profiles by nanoparticle distribution 30 or spatial modulation of a light wave 31 , 32 . The photothermal control enabled all-optical light modulation based on local tuning of the birefringence of liquid crystals 33 , the generation of adjustable thermal lenses 34 , 35 , or the implementation of thermally driven wavefront shaping with multiple photothermal lenses 36 , 37 .…”
Spatial light modulators have become an essential tool for advanced microscopy, enabling breakthroughs in 3D, phase, and super-resolution imaging. However, continuous spatial-light modulation that is capable of capturing sub-millisecond microscopic motion without diffraction artifacts and polarization dependence is challenging. Here we present a photothermal spatial light modulator (PT-SLM) enabling fast phase imaging for nanoscopic 3D reconstruction. The PT-SLM can generate a step-like wavefront change, free of diffraction artifacts, with a high transmittance and a modulation efficiency independent of light polarization. We achieve a phase-shift > π and a response time as short as 70 µs with a theoretical limit in the sub microsecond range. We used the PT-SLM to perform quantitative phase imaging of sub-diffractional species to decipher the 3D nanoscopic displacement of microtubules and study the trajectory of a diffusive microtubule-associated protein, providing insights into the mechanism of protein navigation through a complex microtubule network.
“…More recently, the possibility to create ultra-local heat sources has also found a lot of innovative applications, namely in photothermal cancer therapy [1][2][3] nanosurgery, 4 drug delivery, [5][6][7] photothermal imaging, 8 photoacoustic imaging, 9 magnetic recording, 10 nanochemistry, 11 thermonics, 12 optofluidics, 13 and temperature shaping. 14 However, despite the recent progress of the thermoplasmonics field, quantitative temperature measurements at the nanoscale remain a real challenge. To access this local information, scanning probes and far-field optical techniques have been developed.…”
Temperature characterization and quantification at the nanoscale remain core challenges in applications based on photoinduced heating of nanoparticles. Here, we propose a new approach to obtain quantitative temperature measurements on individual nanoparticles by combining modulated photothermal stimulation and heterodyne digital holography. From full-field reconstructed holograms, temperature is determined with a precision of 0.3 K via a simple approach without requiring any calibration or fitting parameters. As an application, the dependence of temperature on the aspect ratio of gold nanoparticles is investigated. A good agreement with numerical simulation is observed.
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