Microheater

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

Free-standing, thin-film sensors for the trace detection of explosives.

Abstract: In a world focused on the development of cybersecurity, many densely populated areas and transportation hubs are still susceptible to terrorist attacks via improvised explosive devices (IEDs). These devices frequently employ a combination of peroxide based explosives as well as nitramines, nitrates, and nitroaromatics. Detection of these explosives can be challenging due to varying chemical composition and the extremely low vapor pressures exhibited by some explosive compounds. No electronic trace detection system currently exists that is capable of continuously monitoring both peroxide based explosives and certain nitrogen based explosives, or their precursors, in the vapor phase. Recently, we developed a thermodynamic sensor that can detect a multitude of explosives in the vapor phase at the parts-per-trillion (ppt) level. The sensors rely on the catalytic decomposition of the explosive and specific oxidation-reduction reactions between the energetic molecule and metal oxide catalyst; i.e. the heat effects associated with catalytic decomposition and redox reactions between the decomposition products and catalyst are measured. Improved sensor response and selectivity were achieved by fabricating free-standing, ultrathin film (1 µm thick) microheater sensors for this purpose. The fabrication method used here relies on the interdiffusion mechanics between a copper (Cu) adhesion layer and the palladium (Pd) microheater sensor. A detailed description of the fabrication process to produce a free-standing 1 µm thick sensor is presented.

A microfluidic chip for rapid analysis of DNA melting curves for BRCA2 mutation screening.

Abstract: A microfluidic chip integrated with a microheater and a luminescent temperature sensor for rapid, spatial melting curve analysis was developed and applied for the screening of a breast cancer gene fragment. The method could detect genetic differences in around 3 minutes total for the whole procedure, which is much faster than established procedures. A microfabrication technique was developed to allow for bonding of a temperature sensing thin film and a Pt microheater with PDMS and the chips could be employed to generate and measure thermal gradients and the fluorescence intensity of stained DNA through multispectral optical imaging. The sensing layer consisting of poly(styrene-co-acrylonitrile) and a tris(1,10-phenanthroline)ruthenium(ii) temperature probe was generated by blade coating on a glass substrate with an attached Pt microheater. Calibration of the temperature between 20 and 90 °C yielded an overall resolution of around 0.13 K. The chip was employed for the screening of the BRCA 2 breast cancer gene; BRCA2 exon 5 was differentiated by its mutant rs80359463 by a 1.1 K difference in melting temperature and two fragments of BRCA2 exon 11 were differentiated by their mutants rs276174826 and rs876660311 by 0.7 K and 2.0 K, respectively. The standard deviations were between 0.1 and 0.5 K. Capable of detecting fluorescence in the DNA and temperature simultaneously and being imaged in a customized assembly, this microchip can be used to screen for mutations in a variety of DNA samples in disease diagnosis and prognosis.

A Built-In Temperature Sensor in an Integrated Microheater

Abstract: Chip-based microheaters have been widely used in many applications, including gas sensors, flow meters, mass sensors, and polymerase chain reaction chambers, where accurate monitoring of temperature is critical The temperature measurement is conventionally done with the aid of a separate sensor, which may add to the cost and inaccuracy In this paper, a built-in temperature sensing method is provided for the microheaters The resistor-based microheater relies on Joule heating mechanism and its resistance is dependent upon its own body temperature, implying that the microheater has an inherent temperature sensing mechanism It is found that an intermittent temperature sampling in the middle of the heating cycle does not disturb the body temperature if the temperature sampling voltage and pulsewidth are sufficiently low and short, respectively The built-in temperature sensing is attributed to the electrical time constant being few orders of magnitude smaller than the thermal time constant The temperature estimation results using the built-in method show excellent agreement with the benchmark measurements from an infrared pyrometer

Thermoelectric gas sensor made into microelement

Abstract: PROBLEM TO BE SOLVED: To provide a thermoelectric gas sensor, made into a microelement, particularly an inexpensive contact combustion type micro gas sensor, capable of identifying the gas kind from a combustible mixed gas, using a simple structure. SOLUTION: This micro thermoelectric gas sensor comprises a thermoelectric conversion part, a microheater, a catalyst layer formed on the microheater and heated by the microheater, the catalyst layer working as a catalyst catalytically burning a combustible gas, and a sensor part including an electrode pattern therefor, which are formed on the membrane of a predetermined thickness. According to this, power consumption can be reduced, and high sensitivity concentration measurement and high-speed response can be attained. COPYRIGHT: (C)2006,JPO&NCIPI