Microheater

About: Microheater is a research topic. Over the lifetime, 814 publications have been published within this topic receiving 12478 citations.

On-Chip Gel-Valve Using Photoprocessable Thermoresponsive Gel

Abstract: Microfluidic chips are powerful tools for biochemical experiments. High speed and precise flow control can be achieved by using microvalves on a chip. Several types of microvalves that can be integrated into a microfluidic chip have been reported. Among them, gel microvalves have certain advantages over other valves because of their soft structure, which will contribute to prevent mechanical damage the cells passing though the valve. Here we use Bioresist, a photoprocessable thermoresponsive gel, as a key component of the microvalve. Since Bioresist is photopatternable, we can create any arbitrary 2D shape from the thermoresponsive gel using photolithography. Moreover, Bioresist has the unique feature of a phase transition around 30°C, and swells and shrinks repeatedly with temperature change. By integrating the patterned thermoresponsive gel with a microheater, we developed a gel actuator and designed a gel-valve. The gel-valve has the advantages of a simple actuation mechanism: high leakage pressure, high speed actuation and low power consumption. The valve is biocompatible and easily integrated into a chip by using conventional photolithography. Using this valve, we achieved on-chip flow control, and applied it to cell sorting on a chip.

Exploitation of an integrated microheater on QCM sensor in particulate matter measurements

Abstract: Most QCM-based devices devoted to PM measurement use substrates of various kinds to collect and retain particles. The novelty of this work is the possibility to use an integrated microheater actuator to change the substrate collecting features during the particulate adsorption. In fact, this paper presents preliminary results about the exploitation of a HQCM (Heated Quartz Crystal Microbalance) in particulate matter (PM) measurements. HQCM is a 10 MHz quartz crystal microbalance with a microheater and a resistive temperature detector (RTD) implemented on its surface. The effects of the sensor surface temperature (T 1 = 20 °C and T 2 = 80 °C) on the PM detection have been studied by a suitable particulate measurement system, where the HQCM coated by grease, worked both as impaction plate and mass sensor. HQCM was tested providing to it a sequence of impulses of microsphere of Cerium (IV) oxide dispersed in synthetic air (715 μg/m 3 of PM 2.5 and 43 μg/m 3 of PM 1 , lasting 1 min) and recording the consequent resonant frequency shift. The results have shown that the HQCM was able to detect PM both at T = 20 °C and at 80° C. Grease coated HQCM exhibited a good frequency stability at T = 80 °C (± 5 Hz) with a negligible grease mass loss during several heating cycles. Furthermore, the results have shown that the surface temperature changes the collection capacity. In particular at higher temperature (80 °C) the frequency change was 2.5 times greater than that at lower temperature (20 °C).

On-Chip Tuning of the Resonant Wavelength in a High-Q Microresonator Integrated with a Microheater

Abstract: We report on fabrication of a microtoroid resonator of a high-quality (high-Q) factor integrated with an on-chip microheater. Both the microresonator and microheater are fabricated using femtosecond laser three-dimensional (3-D) micromachining. The microheater, which is located about 200 µm away from the microresonator, has a footprint size of 200 µm × 400 µm. Tuning of the resonant wavelength in the microresonator has been achieved by varying the voltage applied on the microheater. The response time of the integrated chip is less than 10 seconds.

Electro-Thermal Simulation & Characterization of a Microheater for SMO Gas Sensors

Abstract: The microheater is an important part of a semiconducting metal oxide gas sensor, as its primary function is to heat up the sensitive layer to a desired temperature. The operating temperature of the sensor depends on the sensitive material used and the species of the target gases. Therefore, an accurate extraction of the sensor active area temperature as a function of the applied power is critical for device characterization. These measurements are experimentally challenging due to the extremely small sensing surface area, down to a few tens of $\mu \text{m}^{2}$ , resulting in the need to develop new measurement approaches. In this paper, quantitative testing methods based on platinum and chrome silicon (CrSi) resistance thermometry, as well as a qualitative testing method (light glow) have been carried out to measure the power consumption of two different devices. CrSi has been used as a temperature sensor due to its ability to detect temperatures above 450 °C by acting as a phase-change material. For accurate measurements of temperature distribution, the presented gas sensors are equipped with three configurations of resistive temperature detectors at different locations. To further analyze a sample closed-membrane sensor, finite-element simulations were performed and an analytical model was designed and compared with experimentals. [2017–0228]