Coupled Superhydrophilic PMMA Film with Inverted Pyramid Microstructures for Antireflection and Antifogging Properties

Transparent substrates with antifogging and antireflection ability are of extreme significance for optical devices, because they alleviate performance loss and maintenance costs. Here, we reported that a multifunctional film, with excellent mechanical properties, can be fabricated on the PMMA surface via the micro-transfer printing method. In particular, the synergistic effect of the inverted pyramid microstructure and SiO2 nanoparticles gives the film excellent antireflective, superhydrophilic and antifogging properties, and the silica sol firmly adheres to the PMMA substrate via the silane coupling agent, which exhibits an encouraging prospect of practical applications from lenses for personal and sports eyewear to transparent displays and sensors, etc.

Design of Precision Hot Embossing Machine for Micro-Patterning on PMMA

A microfluidic chip requires micro-channels to be created on a substrate. This paper focuses on the design and development of a precision hot embossing machine for replication of microstructures on a PMMA substrate. Kinematic coupling using three spherical balls in radial v-grooves is used to achieve precise positioning of the mold insert with the base. Flexure based parallel guidance mechanism is used for one DOF motion required for the embossing process. The mechanism allows the motion of the mold normal to the substrate surface. Flexure based kinematic coupling with the thermal center is designed to mitigate thermal stress build-up during heating and cooling of the mold insert. An Arduino-based micro-controller is developed to control the temperature profile during the process. A prototype is fabricated and experiments are performed with an aluminium mold insert on a PMMA substrate. The result shows the feasibility of the concept and the set-up can be used to develop a cost-effective precision hot embossing machine for creating micro-patterns for microfluidic applications.

Fabrication and Characterization of Flexible Thermoelectric Generators Using Micromachining and Electroplating Techniques

This study involves the fabrication and measurement of a flexible thermoelectric generator (FTG) using micromachining and electroplating processes. The area of the FTG is 46 × 17 mm2, and it is composed of 39 thermocouples in series. The thermoelectric materials that are used for the FTG are copper and nickel. The fabrication process involves patterning a silver seed layer on the polymethyl methacrylate (PMMA) substrate using a computer numerical control (CNC) micro-milling machine. Thermoelectric materials, copper and nickel, are deposited on the PMMA substrate using an electroplating process. An epoxy polymer is then coated onto the PMMA substrate. Acetone solution is then used to etch the PMMA substrate and to transfer the thermocouples to the flexible epoxy film. The FTG generates an output voltage (OV) as the thermocouples have a temperature difference (ΔT) between the cold and hot parts. The experiments show that the OV of the FTG is 4.2 mV at ΔT of 5.3 K and the output power is 429 nW at ΔT of 5.3 K. The FTG has a voltage factor of 1 μV/mm2K and a power factor of 19.5 pW/mm2K2. The FTG reaches a curvature of 20 m−1.

A NOVEL METHOD FOR RAPID FABRICATION OF PMMA MICROFLUIDIC CHIP BY LASER CUTTING AND SEALING INTEGRATION

In this paper, we present a new method that is capable of manufacturing microfluidic chips of polymethyl methacrylate (PMMA) rapidly and cheaply. This technique, which we call Tape adhering-Laser Cutting and Sealing Integration (TLCSI), only utilizes a CO2 laser and a piece of double-sided tape to produce a microfluidic chip in several minutes. It only has three main steps. First, the double-sided tape sticks to the surface of a PMMA substrate. Second, the microchannel should be cut on the surface of the double-sided tape. At last, a PMMA cover plate with liquid pools is pressed onto the surface of the double-sided tape and a CO2 laser is used to cut edges of the chip for sealing the chip. We present a qualified microfluidic chip with regular microchannels and sealing strength of 1.2[Formula: see text]Mpa. Compared with most current fabrication methods, TLCSI is a quick and cost-effective way to produce microfluidic chips of PMMA.