Ultrafast Laser Fabrication of Functional Biochips: New Avenues for Exploring 3D Micro- and Nano-Environments

Developing organs-on-chips for biomedical applications

In recent years, organs-on-chips have been arousing great interest for their bionic and stable construction of crucial human organs in vitro. Compared with traditional animal models and two-dimensional cell models, organs-on-chips could not only overcome the limitations of species difference and poor predict ability but also be capable of reappearing the complex cell-cell interaction, tissue interface, biofluid and other physiological conditions of humans. Therefore, organs-on-chips have been regarded as promising and powerful tools in diverse fields such as biology, chemistry, medicine and so on. In this perspective, we present a review of organs-on-chips for biomedical applications. After introducing the key elements and manufacturing craft of organs-on-chips, we intend to review their cut-edging applications in biomedical fields, incorporating biological analysis, drug development, robotics and so on. Finally, the emphasis is focused on the perspectives of organs-on-chips.

Effect of varied beam diameter of picosecond laser on Foturan glass volume microprocessing

Foturan glass is a photosensitive transparent material which has attracted much interest for microfluidic applications due to possibility of volume processing by ultrafast lasers. In this work, we have investigated the effect of picosecond laser on volume processing in Foturan glass when varying the beam diameter incident on a lens. To this end, specific laser focusing configurations have been designed using raytracing models and an analysis protocol has been developed in the lens focusing region in order to describe the focal point displacement occurring at the variation of the incident laser beam diameter. The numerically simulated results were explained in association with Rayleigh length and found to be in good agreement with the experimental data obtained at well-defined conditions. Specifically, it was found that the hollow microstructures developed by thermal treatment and chemical etching after laser irradiation were significantly displaced along the propagation direction when the incident beam diameter varied in the range of 1-3.5 times. This approach aims to bring an essential contribution to the field of ultrashort pulse lasers micro- and nanoprocessing in transparent materials proving that the laser beam focus position and its size can be precisely controlled with high precision by automated optics for the variation of incident laser beam diameter in predefined conditions. This approach has the potential for laser multi-beam processing at various volume depths using the same optics setup and may even be applicable to two-photon excitation microscopy. On the other hand, the processing protocol in Foturan glass may allow understanding transparent material modification by tailoring laser beam characteristics.

Femtosecond Laser Processing Technology for Anti-Reflection Surfaces of Hard Materials

The anti-reflection properties of hard material surfaces are of great significance in the fields of infrared imaging, optoelectronic devices, and aerospace. Femtosecond laser processing has drawn a lot of attentions in the field of optics as an innovative, efficient, and green micro-nano processing method. The anti-reflection surface prepared on hard materials by femtosecond laser processing technology has good anti-reflection properties under a broad spectrum with all angles, effectively suppresses reflection, and improves light transmittance/absorption. In this review, the recent advances on femtosecond laser processing of anti-reflection surfaces on hard materials are summarized. The principle of anti-reflection structure and the selection of anti-reflection materials in different applications are elaborated upon. Finally, the limitations and challenges of the current anti-reflection surface are discussed, and the future development trend of the anti-reflection surface are prospected.

Recent Developments in Artificial Super-Wettable Surfaces Based on Bioinspired Polymeric Materials for Biomedical Applications

Inspired by nature, significant research efforts have been made to discover the diverse range of biomaterials for various biomedical applications such as drug development, disease diagnosis, biomedical testing, therapy, etc. Polymers as bioinspired materials with extreme wettable properties, such as superhydrophilic and superhydrophobic surfaces, have received considerable interest in the past due to their multiple applications in anti-fogging, anti-icing, self-cleaning, oil-water separation, biosensing, and effective transportation of water. Apart from the numerous technological applications for extreme wetting and self-cleaning products, recently, super-wettable surfaces based on polymeric materials have also emerged as excellent candidates in studying biological processes. In this review, we systematically illustrate the designing and processing of artificial, super-wettable surfaces by using different polymeric materials for a variety of biomedical applications including tissue engineering, drug/gene delivery, molecular recognition, and diagnosis. Special attention has been paid to applications concerning the identification, control, and analysis of exceedingly small molecular amounts and applications permitting high cell and biomaterial cell screening. Current outlook and future prospects are also provided.

Lab-on-a-Chip Platforms as Tools for Drug Screening in Neuropathologies Associated with Blood-Brain Barrier Alterations

Lab-on-a-chip (LOC) and organ-on-a-chip (OOC) devices are highly versatile platforms that enable miniaturization and advanced controlled laboratory functions (i.e., microfluidics, advanced optical or electrical recordings, high-throughput screening). The manufacturing advancements of LOCs/OOCs for biomedical applications and their current limitations are briefly discussed. Multiple studies have exploited the advantages of mimicking organs or tissues on a chip. Among these, we focused our attention on the brain-on-a-chip, blood-brain barrier (BBB)-on-a-chip, and neurovascular unit (NVU)-on-a-chip applications. Mainly, we review the latest developments of brain-on-a-chip, BBB-on-a-chip, and NVU-on-a-chip devices and their use as testing platforms for high-throughput pharmacological screening. In particular, we analyze the most important contributions of these studies in the field of neurodegenerative diseases and their relevance in translational personalized medicine.

High Repetition Rate UV versus VIS Picosecond Laser Fabrication of 3D Microfluidic Channels Embedded in Photosensitive Glass

Glass is an alternative solution to polymer for the fabrication of three-dimensional (3D) microfluidic biochips. Femtosecond (fs) lasers are nowadays the most promising tools for transparent glass processing. Specifically, the multiphoton process induced by fs pulses enables fabrication of embedded 3D channels with high precision. The subtractive fabrication process creating 3D hollow structures in glass, known as fs laser-assisted etching (FLAE), is based on selective removal of the laser-modified regions by successive chemical etching in diluted hydrofluoric acid solutions. In this work we demonstrate the possibility to generate embedded hollow channels in photosensitive Foturan glass volume by high repetition rate picosecond (ps) laser-assisted etching (PLAE). In particular, the influence of the critical irradiation doses and etching rates are discussed in comparison of two different wavelengths of ultraviolet (355 nm) and visible (532 nm) ranges. Fast and controlled fabrication of a basic structure composed of an embedded micro-channel connected with two open reservoirs, commonly used in the biochip design, are achieved inside glass. Distinct advantages such as good aspect-ratio, reduced processing time for large areas, and lower fabrication cost are evidenced.

Editorial for the Special Issue on Ultrafast Laser Fabrication for Lab-on-a-Chip

Ultrafast laser microfabrication is a very powerful method for producing integrated devices in transparent materials [1].[...].