Two-step hybrid process of movable part inside glass substrate using ultrafast laser

Combined Femtosecond Laser Glass Microprocessing for Liver-on-Chip Device Fabrication

Nowadays, lab-on-chip (LOC) devices are attracting more and more attention since they show vast prospects for various biomedical applications. Usually, an LOC is a small device that serves a single laboratory function. LOCs show massive potential for organ-on-chip (OOC) device manufacturing since they could allow for research on the avoidance of various diseases or the avoidance of drug testing on animals or humans. However, this technology is still under development. The dominant technique for the fabrication of such devices is molding, which is very attractive and efficient for mass production, but has many drawbacks for prototyping. This article suggests a femtosecond laser microprocessing technique for the prototyping of an OOC-type device-a liver-on-chip. We demonstrate the production of liver-on-chip devices out of glass by using femtosecond laser-based selective laser etching (SLE) and laser welding techniques. The fabricated device was tested with HepG2(GS) liver cancer cells. During the test, HepG2(GS) cells proliferated in the chip, thus showing the potential of the suggested technique for further OOC development.

Sapphire Selective Laser Etching Dependence on Radiation Wavelength and Etchant

Transparent and high-hardness materials have become the object of wide interest due to their optical and mechanical properties; most notably, concerning technical glasses and crystals. A notable example is sapphire-one of the most rigid materials having impressive mechanical stability, high melting point and a wide transparency window reaching into the UV range, together with impressive laser-induced damage thresholds. Nonetheless, using this material for 3D micro-fabrication is not straightforward due to its brittle nature. On the microscale, selective laser etching (SLE) technology is an appropriate approach for such media. Therefore, we present our research on C-cut crystalline sapphire microprocessing by using femtosecond radiation-induced SLE. Here, we demonstrate a comparison between different wavelength radiation (1030 nm, 515 nm, 343 nm) usage for material modification and various etchants (hydrofluoric acid, sodium hydroxide, potassium hydroxide and sulphuric and phosphoric acid mixture) comparison. Due to the inability to etch crystalline sapphire, regular SLE etchants, such as hydrofluoric acid or potassium hydroxide, have limited adoption in sapphire selective laser etching. Meanwhile, a 78% sulphuric and 22% phosphoric acid mixture at 270 °C temperature is a good alternative for this process. We present the changes in the material after the separate processing steps. After comparing different processing protocols, the perspective is demonstrated for sapphire structure formation.

A 3D Miniaturized Glass Magnetic-Active Centrifugal Micropump Fabricated by SLE Process and Laser Welding

A miniaturized pump to manipulate liquid flow in microchannels is the key component of microfluidic devices. Many researchers have demonstrated active microfluidic pumps, but most of them still required additional large peripherals to operate their micropumps. In addition, those micropumps were made of polymer materials so that their application may be limited to a variety of fields that require harsh conditions at high pressures and temperatures or organic solvents and acid/base. In this work, we present a 3D miniaturized magnetic-driven glass centrifugal pump for microfluidic devices. The pump consists of a volute structure and a 3D impeller integrated with two magnet disks of Φ1 mm. The 3D pump structure was 13 mm × 10.5 mm × 3 mm, and it was monolithically fabricated in a fused silica sheet by selective laser-induced etching (SLE) technology using a femtosecond laser. The pump operation requires only one motor rotating two magnets. It was Φ42 mm × 54 mm and powered by a battery. To align the shaft of the motor to the center of the 3D glass pump chip, a housing containing the motor and the chip was fabricated, and the overall size of the proposed micropump device was 95 mm × 70 mm × 75 mm. Compared with other miniaturized pumps, ours was more compact and portable. The output pressure of the fabricated micropump was between 215 Pa and 3104 Pa, and the volumetric flow rate range was 0.55 mL/min and 7.88 mL/min. The relationship between the motor RPM and the impeller RPM was analyzed, and the flow rate was able to be controlled by the RPM. With its portability, the proposed pump can be applied to produce an integrated and portable microfluidic device for point-of-care analysis.