Microheater

About: Microheater is a(n) research topic. Over the lifetime, 814 publication(s) have been published within this topic receiving 12478 citation(s).

High Surface Area MoS2/Graphene Hybrid Aerogel for Ultrasensitive NO2 Detection

Abstract: A MoS2/graphene hybrid aerogel synthesized with two-dimensional MoS2 sheets coating a high surface area graphene aerogel scaffold is characterized and used for ultrasensitive NO2 detection. The combination of graphene and MoS2 leads to improved sensing properties with the graphene scaffold providing high specific surface area and high electrical and thermal conductivity and the single to few-layer MoS2 sheets providing high sensitivity and selectivity to NO2. The hybrid aerogel is integrated onto a low-power microheater platform to probe the gas sensing performance. At room temperature, the sensor exhibits an ultralow detection limit of 50 ppb NO2. By heating the material to 200 °C, the response and recovery times to reach 90% of the final signal decrease to <1 min, while retaining the low detection limit. The MoS2/graphene hybrid also shows good selectivity for NO2 against H2 and CO, especially when compared to bare graphene aerogel. The unique structure of the hybrid aerogel is responsible for the ultrasensitive, selective, and fast NO2 sensing. The improved sensing performance of this hybrid aerogel also suggests the possibility of other 2D material combinations for further sensing applications.

Thermocapillary actuation of droplets on chemically patterned surfaces by programmable microheater arrays

Abstract: We have designed a microfluidic device for the actuation of liquid droplets or continuous streams on a solid surface by means of integrated microheater arrays. The microheaters provide control of the surface temperature distribution with high spatial resolution. These temperature gradients locally alter the surface tension along droplets and thin films thus propelling the liquid toward the colder regions. In combination with liquophilic and liquophobic chemical surface patterning, this device can be used as a logistic platform for the parallel and automated routing, mixing and reacting of a multitude of liquid samples, including alkanes, poly(ethylene glycol) and water.

Single quantum dots as local temperature markers.

Abstract: This work describes noncontact, local temperature measurements using wavelength shifts of CdSe quantum dots (QDs). Individual QDs are demonstrated to be capable of sensing temperature variations and reporting temperature changes remotely through optical readout. Temperature profiles of a microheater under different input voltages are evaluated based on the spectral shift of QDs on the heater, and results are consistent with a one-dimensional electrothermal model. The theoretical resolution of this technique could go down to the size of a single quantum dot using far-field optics for temperature characterizations of micro/nanostructures.

Wavelength-tunable silicon microring modulator.

Abstract: We present a wavelength-tunable, compact, high speed and low power silicon microring modulator. With a ring radius of 5 microm, we demonstrate a modulator with a high speed of 12.5 Gbps and a driving voltage of 3 V to achieve approximately 6 dB extinction ratio in high speed measurement. More importantly, tunability of the resonant wavelength is accomplished by means of a microheater on top of the ring, with an efficiency of 2.4 mW/nm (2.4 mW is needed to tune the resonant wavelength by 1 nm). This device aims to solve the narrow bandwidth problem of silicon microcavity modulators and increase the data bandwidth in optical interconnect systems.

Microfluidic actuation by modulation of surface stresses

Abstract: We demonstrate the active manipulation of nanoliter liquid samples on the surface of a glass or silicon substrate by combining chemical surface patterning with electronically addressable microheater arrays. Hydrophilic lanes designate the possible routes for liquid migration while activation of specific heater elements determine the trajectories. The induced temperature fields spatially modulate the liquid surface tension thereby providing electronic control over the direction, timing, and flow rate of continuous streams or discrete drops. Temperature maps can be programed to move, split, trap, and mix ultrasmall volumes without mechanically moving parts and with low operating voltages of 2–3 V. This method of fluidic actuation allows direct accessibility to liquid samples for handling and diagnostic purposes and provides an attractive platform for palm-sized and battery-powered analysis and synthesis.