Micro hot embossing of thermoplastic polymers is a promising process to fabricate high precision and high quality features in micro/nano scale. This technology has experienced more than 40 years development and has been partially applied in industrial production. Three modes of micro hot embossing including plate-to-plate, roll-to-plate and roll-to-roll have been successively developed to meet the increasing demand for large-area patterned polymeric films. This review surveys recent progress of micro hot embossing in terms of polymeric material behavior, embossing process and corresponding apparatus. Besides, challenges and innovations in mold fabrication techniques are comprehensively summarized and industrial applications are systematically cataloged as well. Finally, technical challenges and future trends are presented for micro hot embossing of thermoplastic polymers.

https://iopscience.iop.org/article/10.1088/0960-1317/24/1/013001/pdf

Micro hot embossing of thermoplastic polymers: a review

Microflow extraction: A review of recent development

Review on ultrasonic fabrication of polymer micro devices.

In this study, we present a novel rapid hot micro-embossing technique utilizing micro-patterned silicon stampers coated with a newly developed carbide-bonded graphene network to implement rapid heating and cooling. The graphene coating layer is highly thermally conductive and a ~ 45 nm thick coating layer on silicon wafer could serve as a highly efficient heating film because of its high electrical conductivity of 1.98 × 104 S/m and low surface resistivity of 20.4 Ω. Heating rates of 5–10 °C/s could be achieved by employing a DC operating voltage under 50 V to allow the contact surface temperature of the stamper and the polymer substrate reaching glass transition temperature within 10 s for rapid embossing of microscale features. Since the graphene coating is very thin, the stamper surface could be cooled rapidly after embossing to keep the cycle time shorter than 25 s. This novel hot embossing technique was successfully implemented to imprint microchannel and microlens arrays on thermoplastic polymer substrates with high precision. Compared with conventional hot embossing, our facile method could achieve better replication fidelity with much less cycle time.

Rapid hot embossing of polymer microstructures using carbide-bonded graphene coating on silicon stampers

A review on microfabrication of thermoplastic polymer-based microneedle arrays

Ultrasonic hot embossing is a new process for fast and low-cost production of micro systems from polymer. Investment costs are on the order of 20.000 € and cycle times are a few seconds. Microstructures are fabricated on polymer foils and can be combined to three-dimensional systems by ultrasonic welding.

https://www.mdpi.com/2072-666X/2/2/157/pdf

Ultrasonic Hot Embossing

Slug length monitoring in liquid–liquid Taylor-flow integrated in a novel PVDF micro-channel

A concept for battery-less remote controls has been developed based on mechanically actuated beams and micro whistles generating ultrasound signals These signals need to be frequency or time coded to increase the number of signals which can be distinguished from each other and environmental ultrasound Several designs for generating coded ultrasonic signals have been investigated

http://iopscience.iop.org/article/10.1088/0960-1317/19/7/074002/pdf

Coded ultrasonic remote control without batteries

Ultrasonic hot embossing allows the fabrication of micro structures from polymer films by moulding from a master tool. The fabrication process is completed within seconds and the investment costs are low. With micro patterned tools, structured surfaces can be created on one or both sides of polymer films. For micro whistles and micro fluidic devices such as micro mixers or flow sensors, sealed structures are created by welding a cover film on embossed structures. Furthermore, moulded interconnection devices can be fabricated by welding polymer coated metal films onto polymers.

K. Burlage

Papers

Review on ultrasonic fabrication of polymer micro devices.

Ultrasonic Hot Embossing

Slug length monitoring in liquid–liquid Taylor-flow integrated in a novel PVDF micro-channel

Coded ultrasonic remote control without batteries

Ultrasonic Hot Embossing and Welding of Micro Structures