Topic
Microheater
About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.
Papers published on a yearly basis
Papers
More filters
10 Jun 2022
TL;DR: In this paper , the authors evaluated the feasibility of using miniaturized asymmetric structures to move liquid droplets and understand the driving mechanism of liquid droplet motion on the ratchets.
Abstract: The main objective of this study is to evaluate the feasibility of using miniaturized asymmetric structures to move liquid droplets and understand the driving mechanism. We developed the fabrication process for large area topological ratchets with the period ranging from millimeter down to sub-micrometer using micromachining techniques. Non-wetting superhydrophobic surfaces were successfully fabricated using soft UV or thermal nanoimprint lithography, reactive ion etching by oxygen plasma, and chemical surface modification by fluorinated silane vapor deposition. An accurate and reproducible experimental setup equipped with high speed camera and automatic injection system was established. Image processing tools allowed us to obtain various critical information related droplet motion and behavior along the ratchets surface. Various influences on the motion such as the surface temperature, ratchets dimension, surface wettability, droplet volume, kind of liquid, initial impact speed of droplet, polymer additive, and surface slope were systematically investigated for miniaturized non-wetting asymmetric ratchets. It is observed that the droplet motion on the ratchets is strongly dependent on the ratchets dimensions as well as the surface temperature. Extremely fast water droplet motion was achieved from the sub-micrometer ratchets near the Leidenfrost temperature. Even though the Leidenfrost-miniaturized ratchets system can be considered as an efficient pumping and cooling component, further intensive study to reduce the operating temperature and drive the liquid motion within microchannel is required for the broad range of applications.
TL;DR: In this paper , a microfluidic reaction well was used to monitor the temperature within the reaction well with ± 1 °C precision, which is similar to a conventional thermocycler.
Abstract: The production of microfluidic PCR devices within lab settings in a straightforward process and large numbers is limited due to complex methods of fabrication and high cost of development. In this study, we developed a unique disposable, low-cost, and easy-to-fabricate microfluidic PCR chip, comprised of a passive micromixer, reaction well, microheater, and a dynamic temperature control system. In addition to being compact, this device has the advantages of microfluidic PCR systems, such as low power and sample consumption, as well as being disposable and easy to fabricate. The disposable part of the chip is easy to fabricate and eliminates the run-to-run carryover contamination while its integration with a reusable heating system reduces the cost of producing a micro PCR device. The geometry of the micromixer and the pattern of microheater electrodes are analyzed through experiments to achieve comparable amplification to a conventional thermocycler. The temperature control system is designed to monitor the temperature within the reaction well with ±1 °C precision. Finally, the reliability and repeatability of the microfluidic device were verified by amplifying lambda (λ) DNA. The proposed device demonstrated high-quality amplification comparable to the conventional PCR and is an adaptable and low-cost on-chip PCR device for reliable molecular diagnostics.
TL;DR: In this paper, the grain size of a 50 nm thick as-grown Pt film/heater was found to be nm when post-annealed at a temperature of C for 30 min, compared with when electric current is run through a heater.
Abstract: When 50 nm thick Pt microheaters of lateral dimensions μm2 are subjected to high electric power their resistance R rises, as expected. Following an initial rise, however, there is a gradual decrement in R while constant electric power dissipation is maintained. We find that this lowering in R is accompanied by grain growth in the polycrystalline thin Pt film of our heaters. This is confirmed by XRD measurements and SEM imaging. Similar growth in grain size is observed in thin Pt films that are oven-annealed at high temperatures. Thus, we argue that maintaining high power dissipation in a microheater has the same effect on its material structure as post-annealing. We observe the in-plane grain size of a 50 nm thick as-grown Pt film/heater to be nm. When post-annealed at a temperature of C for 30 min, nm, compared with when electric current is run through a heater, we estimate the mean crystalline length to be nm.
14 Nov 2014
TL;DR: In this paper, a microheater line and a temperature sensor line are used to measure the thermal conductivity of a thin plastic substrate using the transient thermal response of the plastic substrate to a heating current.
Abstract: A number of past papers have described experimental techniques for measurement of thermal conductivity of substrates and thin films of technological interest. Nearly all substrates measured in the past are rigid. There is a lack of papers that report measurements on a flexible substrate such as thin plastic. The paper presents an experimental methodology to deposit a thin film microheater device on a plastic substrate. This device, comprising a microheater line and a temperature sensor line is used to measure the thermal conductivity of the plastic substrate using the transient thermal response of the plastic substrate to a heating current. An analytical model describing this thermal response is presented. Thermal conductivity of the plastic substrate is determined by comparison of experimental data with the analytical model. Results described in this paper may aid in development of an understanding of thermal transport in flexible substrates.Copyright © 2014 by ASME