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Kumar R, Dzikonski D, Bekker E, Vornhusen R, Vitali V, Imbrock J, Denz C. Fabrication and mechanical characterization of hydrogel-based 3D cell-like structures. OPTICS EXPRESS 2023; 31:29174-29186. [PMID: 37710723 DOI: 10.1364/oe.496888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/27/2023] [Indexed: 09/16/2023]
Abstract
In this article, we demonstrate the fabrication of 3D cell-like structures using a femtosecond laser-based two-photon polymerization technique. By employing poly(ethylene glycol) diacrylate monomers as a precursor solution, we fabricate 3D hemispheres that resemble morphological and biomechanical characteristics of natural cells. We employ an optical tweezers-based microrheology technique to measure the viscoelastic properties of the precursor solutions inside and outside the structures. In addition, we demonstrate the interchangeability of the precursor solution within fabricated structures without impairing the microstructures. The combination of two-photon polymerization and microrheological measurements by optical tweezers demonstrated here represents a powerful toolbox for future investigations into cell mimic and artificial cell studies.
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Kratz M, Rückle L, Kalupka C, Reininghaus M, Haefner CL. Dynamic correction of optical aberrations for height-independent selective laser induced etching processing strategies. OPTICS EXPRESS 2023; 31:26104-26119. [PMID: 37710479 DOI: 10.1364/oe.493088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 07/05/2023] [Indexed: 09/16/2023]
Abstract
Optical aberrations are a critical issue for tight focusing and high precision manufacturing with ultrashort pulsed laser radiation in transparent media. Controlling the wave front of ultrashort laser pulses enable the correction of low order phase front distortion and significantly enhances the simplification of laser-based manufacturing of 3D-parts in glass. The influence of system-inherent, dominating aberrations such as spherical and astigmatic aberrations affect the focal area, the beam caustic and therefore the focus intensity distribution. We correct these aberrations by means of a spatial light modulator (SLM) for various processing depths in glass thickness of up to 12 mm. This flexible aberration correction significantly simplifies the process control and scanning strategies for the selective laser induced etching process. The influence on the selectivity is investigated by comparing the three different focus conditions of the intrinsic microscope objective aberration corrected, the aberrated and the SLM aberration corrected beam profile. The previously necessary pulse energy adjustment for different z positions in the glass volume is compensated via SLM aberration correction in the end. Furthermore, the spatial extend of the modified and etched area is investigated. In consequence, a simplified scan strategy and depth-independent processing parameters can be achieved for the selective laser induced etching process.
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Laser-Assisted Etching of EagleXG Glass by Irradiation at Low Pulse-Repetition Rate. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12030948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Femtosecond laser micromachining is becoming an established technique for the fabrication of complex three-dimensional structures in glass. The combination of laser writing and chemical etching increases the technique versatility by allowing the fabrication of hollow structures within the bulk material. The possibility to encompass both optical and fluidic components in a single substrate allows us to realize optofluidic devices usable in several application fields. Here, we present new investigations of laser-assisted etching in Eagle XG glass showing good etching conditions at low repetition rates, where thermal effects can be neglected, and low irradiation speeds, which allow for complex microchannel network formation.
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Guo M, Wan J, Yuan W, Zhu X, Chen Y, Wei S. M × N electrically controlled optofluidic matrix switch. APPLIED OPTICS 2021; 60:9981-9988. [PMID: 34807189 DOI: 10.1364/ao.440876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
A completely non-blocking M×N electrically controlled optofluidic matrix switch that uses a 1×3 optical switch with a V-shaped microchannel as the switching unit is proposed. Its light paths and output ports are selected by a micro-actuator matrix and a control circuit. There are few reports of optofluidic matrix switches. Here the given electrostatic micro-actuator and the basic switch structure provide an effective feasible manner for the matrix switch due to the simple and compact structure as well as the operation style. The impacts of microchannels and intersecting waveguides on the switch performance are discussed, and multiple optimization schemes are proposed to reduce the insertion loss efficiently and significantly. The research results indicate that the M×N matrix switch has the advantages of good matrix controllability, simple structure, wide waveband (400-1700 nm), negligible polarization-dependent loss, small insertion loss, and low cross talk. For 1550 nm wavelength, the insertion loss of a 2×6 matrix switch is about 0.17-0.55 dB, and the maximum cross talk is less than -26.8dB. In addition, the performance parameters of a 4×8 matrix switch are given and compared with other reported matrix switches. The proposed M×N matrix switch solves the problem of large insertion loss of general optical matrix switches and can be expanded to a large-scale matrix switch. Moreover, the design of multiple output ports has more flexible applications in systems with multiple branch optical paths and network nodes.
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Edera P, Brizioli M, Zanchetta G, Petekidis G, Giavazzi F, Cerbino R. Deformation profiles and microscopic dynamics of complex fluids during oscillatory shear experiments. SOFT MATTER 2021; 17:8553-8566. [PMID: 34515281 DOI: 10.1039/d1sm01068a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Oscillatory shear tests are widely used in rheology to characterize the linear and non-linear mechanical response of complex fluids, including the yielding transition. There is an increasing urge to acquire detailed knowledge of the deformation field that is effectively present across the sample during these tests; at the same time, there is mounting evidence that the macroscopic rheological response depends on the elusive microscopic behavior of the material constituents. Here we employ a strain-controlled shear-cell with transparent walls to visualize and quantify the dynamics of tracers embedded in various cyclically sheared complex fluids, ranging from almost-ideal elastic to yield stress fluids. For each sample, we use image correlation processing to measure the macroscopic deformation field, and echo-differential dynamic microscopy to probe the microscopic irreversible sample dynamics in reciprocal space; finally, we devise a simple scheme to spatially map the rearrangements in the sheared sample, once again without tracking the tracers. For the yield stress sample, we obtain a wave-vector dependent characterization of shear-induced diffusion across the yielding transition, which is accompanied by a three-order-of-magnitude speed-up of the dynamics and by a transition from localized, intermittent rearrangements to a more spatially homogeneous and temporally uniform activity. Our tracking free approach is intrinsically multi-scale, can successfully discriminate between different types of dynamics, and can be automated to minimize user intervention. Applications are many, as it can be translated to other imaging modes, including fluorescence, and can be used with sub-resolution tracers and even without tracers, for samples that provide intrinsic optical contrast.
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Affiliation(s)
- Paolo Edera
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via F.lli Cervi 93, 20090 Segrate, Italy.
| | - Matteo Brizioli
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via F.lli Cervi 93, 20090 Segrate, Italy.
| | - Giuliano Zanchetta
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via F.lli Cervi 93, 20090 Segrate, Italy.
| | - George Petekidis
- FORTH/IESL and Department of Materials Science and Technology, University of Crete, 71110 Heraklion, Greece
| | - Fabio Giavazzi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via F.lli Cervi 93, 20090 Segrate, Italy.
| | - Roberto Cerbino
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via F.lli Cervi 93, 20090 Segrate, Italy.
- University of Vienna, Faculty of Physics, Boltzmanngasse 5, 1090 Vienna, Austria
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Zamboni R, Zaltron A, Chauvet M, Sada C. Real-time precise microfluidic droplets label-sequencing combined in a velocity detection sensor. Sci Rep 2021; 11:17987. [PMID: 34504237 PMCID: PMC8429775 DOI: 10.1038/s41598-021-97392-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/24/2021] [Indexed: 11/09/2022] Open
Abstract
Droplets microfluidics is broadening the range of Lab on a Chip solutions that, however, still suffer from the lack of an adequate level of integration of optical detection and sensors. In fact, droplets are currently monitored by imaging techniques, mostly limited by a time-consuming data post-processing and big data storage. This work aims to overcome this weakness, presenting a fully integrated opto-microfluidic platform able to detect, label and characterize droplets without the need for imaging techniques. It consists of optical waveguides arranged in a Mach Zehnder's configuration and a microfluidic circuit both coupled in the same substrate. As a proof of concept, the work demonstrates the performances of this opto-microfluidic platform in performing a complete and simultaneous sequence labelling and identification of each single droplet, in terms of its optical properties, as well as velocity and lengths. Since the sensor is realized in lithium niobate crystals, which is also highly resistant to chemical attack and biocompatible, the future addition of multifunctional stages into the same substrate can be easily envisioned, extending the range of applicability of the final device.
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Affiliation(s)
- R Zamboni
- Physics and Astronomy Department, University of Padova, Via Marzolo 8, 35131, Padova, Italy.,Institute of Applied Physics, University of Münster, Corrensstrasse 2/4, 48149, Münster, Germany
| | - A Zaltron
- Physics and Astronomy Department, University of Padova, Via Marzolo 8, 35131, Padova, Italy
| | - M Chauvet
- FEMTO-ST Institute, UMR 6174, University of Bourgogne Franche-Comté, 15B Avenue des Montboucons, 25000, Besançon, France
| | - C Sada
- Physics and Astronomy Department, University of Padova, Via Marzolo 8, 35131, Padova, Italy.
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Multi-frequency passive and active microrheology with optical tweezers. Sci Rep 2021; 11:13917. [PMID: 34230533 PMCID: PMC8260820 DOI: 10.1038/s41598-021-93130-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/21/2021] [Indexed: 11/23/2022] Open
Abstract
Optical tweezers have attracted significant attention for microrheological applications, due to the possibility of investigating viscoelastic properties in vivo which are strongly related to the health status and development of biological specimens. In order to use optical tweezers as a microrheological tool, an exact force calibration in the complex system under investigation is required. One of the most promising techniques for optical tweezers calibration in a viscoelastic medium is the so-called active–passive calibration, which allows determining both the trap stiffness and microrheological properties of the medium with the least a-priori knowledge in comparison to the other methods. In this manuscript, we develop an optimization of the active–passive calibration technique performed with a sample stage driving, whose implementation is more straightforward with respect to standard laser driving where two different laser beams are required. We performed microrheological measurements over a broad frequency range in a few seconds implementing an accurate multi-frequency driving of the sample stage. The optical tweezers-based microrheometer was first validated by measuring water, and then exemplarily applied to more viscous medium and subsequently to a viscoelastic solution of methylcellulose in water. The described method paves the way to microrheological precision metrology in biological samples with high temporal- and spatial-resolution allowing for investigation of even short time-scale phenomena.
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Optical interferometry based micropipette aspiration provides real-time sub-nanometer spatial resolution. Commun Biol 2021; 4:610. [PMID: 34021241 PMCID: PMC8140111 DOI: 10.1038/s42003-021-02121-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/12/2021] [Indexed: 11/09/2022] Open
Abstract
Micropipette aspiration (MPA) is an essential tool in mechanobiology; however, its potential is far from fully exploited. The traditional MPA technique has limited temporal and spatial resolution and requires extensive post processing to obtain the mechanical fingerprints of samples. Here, we develop a MPA system that measures pressure and displacement in real time with sub-nanometer resolution thanks to an interferometric readout. This highly sensitive MPA system enables studying the nanoscale behavior of soft biomaterials under tension and their frequency-dependent viscoelastic response.
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Vitali V, Nava G, Corno A, Pezzotti M, Bragheri F, Paiè P, Osellame R, Ortenzi MA, Cristiani I, Minzioni P, Bellini T, Zanchetta G. Yield stress "in a flash": investigation of nonlinearity and yielding in soft materials with an optofluidic microrheometer. SOFT MATTER 2021; 17:3105-3112. [PMID: 33598667 DOI: 10.1039/d0sm02168g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Yield stress materials deform as elastic solids or flow as viscous liquids, depending on the applied stress, which also allows them to trap particles below a certain size or density threshold. To investigate the conditions for such a transition at the microscale, we use an optofluidic microrheometer, based on the scattering of an infrared beam onto a microbead, which reaches forces in the nN scale. We perform creep experiments on a model soft material composed of swollen microgels, determining the limits of linear response and yield stress values, and observe quantitative agreement with bulk measurements. However, the motion of the microbead, both below and above yielding, reflects distinctive microscale features of the surrounding material, whose plastic rearrangements were investigated by us using small, passive tracers.
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Affiliation(s)
- Valerio Vitali
- Dipartimento di Ingegneria Industriale e dell'Informazione, Università di Pavia, 27100 Pavia, Italy
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