On‐chip laser processing for the development of multifunctional microfluidic chips

Wang, Huan; Zhang, Yong‐Lai; Wang, Wei; Ding, Hong; Sun, Hong–Bo

doi:10.1002/lpor.201600116

Cited by 63 publications

(30 citation statements)

References 211 publications

(270 reference statements)

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“…In this way, very small feature sizes of less than 100 nm can be achieved . Microstructures prepared via DLW have for example been used in microfluidic chips, metamaterials, or as 3D microscaffolds for cell and tissue engineering . Commercial resist mixtures are available that are well suited for the rapid generation of stable structures.…”

Section: Methodsmentioning

confidence: 99%

Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing

et al. 2019

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the laser, where the square of the optical intensity exceeds the threshold needed to initiate polymerization. In this way, very small feature sizes of less than 100 nm can be achieved. [3,4] Microstructures pre pared via DLW have for example been used in microfluidic chips, [5,6] metama terials, [7] or as 3D microscaffolds for cell and tissue engineering. [8] Commercial resist mixtures are available that are well suited for the rapid generation of stable structures. However, when using standard resists, the resulting microstructures are static. In order to further expand the rep ertoire of applications of DLW, new photo resists have to be designed that directly impart functionality onto the structures emerging from the writing process. [9] Our group has been pursuing this goal, pro ducing resists that, e.g., lead to conduc tive, [10] stimuliresponsive, [11] and erasable structures. [12] The mechanical properties of microstructures are critical for their application, especially when used as cell scaf folds. [13] The mechanical properties of microstructures created via DLW can certainly be tuned by careful adjustment of the writing parameters (i.e., laser power and scan speed), but only to a limited extent. [14] Herein, we present the first photoresist for DLW that is capable of generating microstructures whose mechanical properties can be adjusted postwriting, solely The photochemistry of anthracene, a new class of photoresist for direct laser writing, is used to enable visible-light-gated control over the mechanical properties of 3D microstructures post-manufacturing. The mechanical and viscoelastic properties (hardness, complex elastic modulus, and loss factor) of the microstructures are measured over the course of irradiation via dynamic mechanical analysis on the nanoscale. Irradiation of the microstructures leads to a strong hardening and stiffening effect due to the generation of additional crosslinks through the photodimerization of the anthracene functionalities. A relationship between the loss of fluorescence-a consequence of the photodimerization-and changes in the mechanical properties isestablished. The fluorescence thus serves as a proxy read-out for the mechanical properties. These photoresponsive microstructures can potentially be used as "mechanical blank slates": their mechanical properties can be readily adjusted using visible light to serve the demands of different applications and read out using their fluorescence. 3D MicrostructuresDirect laser writing (DLW) is the only manufacturing tech nique capable of producing truly 3D structures on the micro scopic scale. [1] What differentiates DLW from conventional 3Dprinting techniques is the fact that it exploits twophoton absorption (TPA) to initiate polymerizations. While single photon absorption (SPA) is proportional to the optical inten sity, TPA is proportional to the square of the optical intensity. [2] Thus, polymerization will only take place in the focal volume of

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Section: Methodsmentioning

confidence: 99%

Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing

et al. 2019

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“…Materials suitable for fabricating microfluidic chips are usually polymers, glass, silicon, metals, etc. Complex microfluidic channels can be readily fabricated through the combined technologies of lithography and etching . Imprinting and soft lithography technologies have been successfully adopted to efficiently manufacture polymer‐based microfluidic chips.…”

Section: Lspr‐based Poct Devices and Their Applicationmentioning

confidence: 99%

Construction of Plasmonic Nano‐Biosensor‐Based Devices for Point‐of‐Care Testing

Wang

Zhou

2017

Small Methods

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rapid detection technique for the future of home healthcare, mobile healthcare, and public health security. [4] At present, POCTs mainly use conventional lateral flow assays (LFAs) and electrochemical biosensors (such as blood glucose meter) for biosensing. [4,5] To promote the wider application of POCT, new sensing components are expected to appear. Plasmonic nano-biosensor, which stems from the interaction of light and metal nanostructures, is an advancing and promising optical sensor for ultrasensitive, ultrahighspatial-resolution and label-free biodetection. Plasmonic biosensors are mainly divided into propagating surface plasmon resonance (PSPR) and localized surface plasmon resonance (LSPR) biosensors. PSPR arises from the interaction between incident light and a planar metal surface; LSPR confines light to metal nanostructures that are smaller than the wavelength of light, thereby enabling the measurement of the dielectric changes near the metallic surface. [6] Compared with commercially available PSPR sensors, LSPR sensors are simple, cost effective, easy to integrate into miniaturized devices, and suitable for measuring changes in local refractive index (RI) caused by the adsorption of target molecules. [4] Since RI is related to the dielectric property of the environment near the metal nanostructures, LSPR sensors can realize RI biosensing in a convenient way. LSPR nano-biosensors are expected to be easily integrated into miniaturized devices for POCT. Due to the high sensitivity of LSPR biosensor and its possibility to achieve full automation, as therefore to attain time-saving and avoid human error, the integration of LSPR biosensors into portable devices will promote the wider applications of POCT for enhanced healthcare (e.g., on-site diagnosis, personalized medicine, wearable devices, etc.), higher public security (e.g., antiterrorism), environmental monitoring, and food safety. [7][8][9] The evolving of LSPR biosensing into POCT mainly involves four core requirements (Figure 1): i) sensing nanosubstrates with high RI sensitivity; ii) detection strategies to realize specific detection; iii) integrated microfluidic chips for sample pretreatment and multiplex analysis, and iv) portable POCT devices to perform automated and easy-to-use biodetections. Through the advances on plasmonics and nanofabrication in the last few years, highly sensitive as well as large-area producible nanosubstrates for LSPR biosensing have been developed. [10][11][12] In the meanwhile, high specificity and strong anti-interference Next-generation healthcare equipment and devices are in great demand for point-of-care testing (POCT), in view of their applications in rapid disease diagnosis, personalized medicine, portable or mobile health care, nontechnician assays, etc. Localized surface plasmon resonance (LSPR) biosensors, which are based on noble-metal nanostructures and which provide fast, realtime, nonlabeled, and sensitive biochemical detections, have become one of the leading candidates for POCT. The advances in nanofabr...

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“…In addition to tiny structures processed directly on the surface of any type of material, it is also possible for processing inside the bulk of transparent materials to allow the integration of actuators and optical sensors into the microfluidic device without bonding substrates and fabricating lab‐on‐a‐chip devices . Due to extremely high intensities obtained by ultrashort pulses, it is also possible to change the tribological, chemical, and physical properties of surfaces …”

Section: Introductionmentioning

confidence: 99%

“…[12] Among the techniques available for fabrication of microreactors with serpentine channels and T-junctions, femtosecond laser ablation has been drawing attention because it allows machining of a variety of materials, including metals, glass, and ceramics. [14][15][16][17][18] Mechanical micromachining and electric discharge machining wear out the equipment used in the process, while a focused ion beam machining is performed under vacuum; such techniques also require small etching velocities, not allowing fast prototyping. [19] Lithography methods and deep reactive ion etching were adapted from the microelectro-mechanical-systems (MEMS) manufacturing, but are still expensive and complex to operate.…”

Section: Introductionmentioning

confidence: 99%

“…[15] Due to extremely high intensities obtained by ultrashort pulses, it is also possible to change the tribological, chemical, and physical properties of surfaces. [18] Femtosecond laser machining requires translation of a CAD (computer aided design) model to a CNC (computer numerical control) system. It is, therefore, simple to integrate the manufacturing and designing processes.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of a microreactor for synthesizing nanocrystals by computational fluid dynamics

et al. 2018

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Microreactors eliminate batch‐to‐batch variability and allow better control over nanocrystal synthesis. A serpentine microreactor fabricated by femtosecond laser ablation is presented and characterized by computational fluid dynamics, since the micro channels show a trapezoidal cross‐section mainly due to the relatively high numerical aperture of the focusing lens. Mixing, macro and micro, throughout the device was investigated for inlet flow rates between 10–500 μL min−1 and the injection of an inert tracer with the same transport properties of water. The simulation of the whole microreactor enabled the analysis of the formation and destruction of structures. For instance, secondary flows played a major role in mixing behaviour: small flow rates did not promote mixing of the tracer and a stream of pure water even after 43 curved segments, while they were perfectly mixed after 9 segments for higher flow rates. According to the mixing index, the maximum effect of convective mixing was achieved for an inlet flow rate of 250 μL min−1. Tracer dispersion and the mixing index guided a scale‐up process of the microreactor, optimizing the number of curved segments while increasing total throughput. The upscaled design exhibited mixing saturation at 400 μL min−1 and promoted better control of residence time to allow nanocrystal growth.

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On‐chip laser processing for the development of multifunctional microfluidic chips

Cited by 63 publications

References 211 publications

Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing

Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing

Construction of Plasmonic Nano‐Biosensor‐Based Devices for Point‐of‐Care Testing

Analysis of a microreactor for synthesizing nanocrystals by computational fluid dynamics

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