In situ measurement of the effective nonlinear absorption order in multiphoton photoresists

Tomova, Zuleykhan; Λιάρος, Νικόλαος; Razo, Sandra A. Gutierrez; Wolf, Steven; Fourkas, John T.

doi:10.1002/lpor.201600079

Cited by 34 publications

(32 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The processes so far only differ on repetition rate and pulse duration assuming that the laser power is adjustable. Other groups 37–39 have shown that a variation of these two parameters is possible for two-photon polymerization. These results suggest that the repetition rate and pulse duration is adaptable for the polymerization of microneedles towards equal parameters for both laser processes.…”

Section: Resultsmentioning

confidence: 99%

Towards a versatile point-of-care system combining femtosecond laser generated microfluidic channels and direct laser written microneedle arrays

et al. 2019

View full text Add to dashboard Cite

Microneedle-based microfluidic systems have a great potential to become well-accepted medical devices for simple, accurate, and painless drug delivery and lab-on-a-chip diagnostics. In this work, we report on a novel hybrid approach combining femtosecond direct laser written microneedles with femtosecond laser generated microfluidic channels providing an important step towards versatile medical point-of-care systems. Hollow microneedle arrays are fabricated by a laser system designed for two-photon polymerization applications. Compression tests of two different types of truncated cone-shaped microneedle arrays prepared from OrmoComp® give information about the microneedle mechanical strength, and the results are compared to skin insertion forces. Three-dimensional microchannels are directly created inside PMMA bulk material by an ultrashort pulse laser system with vertical channels having adjustable cross-sectional areas, which allow attaching of microneedles to the microfluidic system. A comprehensive parameter study varying pulse duration and repetition rate is performed on two-photon polymerization to identify an optimal laser power range for fabricating microneedles using the same pulse duration and repetition rate as for microchannels. This addresses the advantage of a single laser system process that overcomes complex fabrication methods. A proof of concept flow test with a rhodamine B dye solution in distilled water demonstrates that the combination of microneedles and microchannels qualifies for microfluidic injection and extraction applications.

show abstract

Section: Resultsmentioning

confidence: 99%

Towards a versatile point-of-care system combining femtosecond laser generated microfluidic channels and direct laser written microneedle arrays

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Another approach for measuring the order of effective nonlinear absorption in photoresists is the two‐beam initiation threshold (2‐BIT) technique . This technique involves combining two interleaved pulse trains to expose the photoresist.…”

Section: Indirect Methodsmentioning

confidence: 99%

“…The insets show the absorption spectra of these photoinitiators in methanol, with the effective wavelengths for two‐photon and three‐photon absorption indicated as dashed and dashed‐dotted lines, respectively. (Reproduced with permission . Copyright 2106, Wiley)…”

Section: Indirect Methodsmentioning

confidence: 99%

The Characterization of Absorptive Nonlinearities

Λιάρος

Fourkas

2017

Laser & Photonics Reviews

Self Cite

View full text Add to dashboard Cite

The measurement of the order and magnitude of absorptive nonlinearities is essential to the development and improvement of a wide range of optical materials. This review presents and contrasts some of the most commonly used methods for making such measurements. As background, we introduce the history of, and the essential physics behind, multiphoton absorption (MPA) and phenomena that can interfere with its measurement. We review methods for the direct and indirect measurement of MPA. The direct methods covered include nonlinear transmission, absorption modulation, Z-scan, and spectrally-resolved, two-beam coupling. The indirect methods reviewed, all of which rely on the measurement of multiphoton action cross sections, include nonlinear fluorescence excitation, thermal lensing, MPA-induced photocurrent, and various techniques for determining the order of effective nonlinear absorption in multiphoton absorption polymerization.

show abstract

“…A different method to measure the order of nonlinear absorption was described by Fourkas and coworkers in a technique they named the two-beam initiation threshold (2-BIT) technique [ 23 ]. This method involves splitting an ultrafast laser into two pulse trains, beam #1 and beam #2, and then recombining the pulses with a delay so as to double the repetition rate of the laser.…”

Section: Nonlinearity Ordermentioning

confidence: 99%

“…The insets show the UV-vis absorption spectra and the wavelength equivalent of two- or three- photon absorption by the 800 nm excitation laser. Reproduced from [ 23 ].…”

Section: Figurementioning

confidence: 99%

Two-Photon Polymerization Metrology: Characterization Methods of Mechanisms and Microstructures

LaFratta

Baldacchini

2017

Micromachines

View full text Add to dashboard Cite

The ability to create complex three-dimensional microstructures has reached an unprecedented level of sophistication in the last 15 years. For the most part, this is the result of a steady development of the additive manufacturing technique named two-photon polymerization (TPP). In a short amount of time, TPP has gone from being a microfabrication novelty employed largely by laser specialists to a useful tool in the hands of scientists and engineers working in a wide range of research fields including microfluidics. When used in combination with traditional microfabrication processes, TPP can be employed to add unique three-dimensional components to planar platforms, thus enabling the realization of lab-on-a-chip solutions otherwise impossible to create. To take full advantage of TPP, an in-depth understanding is required of the materials photochemistry and the fabricated microstructures’ mechanical and chemical properties. Thus, we review methods developed so far to investigate the underling mechanism involved during TPP and analytical methods employed to characterize TPP microstructures. Furthermore, we will discuss potential opportunities for using optofluidics and lab-on-a-chip systems for TPP metrology.

show abstract

In situ measurement of the effective nonlinear absorption order in multiphoton photoresists

Cited by 34 publications

References 21 publications

Towards a versatile point-of-care system combining femtosecond laser generated microfluidic channels and direct laser written microneedle arrays

Towards a versatile point-of-care system combining femtosecond laser generated microfluidic channels and direct laser written microneedle arrays

The Characterization of Absorptive Nonlinearities

Two-Photon Polymerization Metrology: Characterization Methods of Mechanisms and Microstructures

Contact Info

Product

Resources

About