Microheater

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

Internal heat therapy for carcinoma of urinary bladder

Abstract: The utility model discloses an internal heat therapy for carcinoma of urinary bladder, which is a medical appliance. The utility model is mainly composed of a conductor, a pressure sensor and a host machine. The conductor is a three-cavity plastic hose, a main cavity, an auxiliary cavity and an air bag cavity are arranged in the hose. The host machine is provided with a temperature control device, a pressure indicator and a temperature indicator, a microheater and a miniature temperature sensor are arranged in the main cavity, and a pressure sensor is arranged in the auxiliary cavity. The microheater and the miniature temperature sensor are separately connected with the temperature control device and temperature indicator of a host machine 3. The pressure sensor and the pressure indicator of the host machine are connected. The utility model carries out artificial heating, dosing and urethral catheterization by the control and display devices to reach the purpose of treatment.

A microheater with temperature stabilization for a scanning probe microscope

Abstract: A microheater for conducting measurements by the scanning probe microscopy technique at various temperatures is described. The temperature stabilization accuracy is 0.05°C in a range of 20–80°C. A negligible temperature drift of 40 nm/°C (in the sample plane) and 100 nm/°C (along the normal) allows the study of temperature-dependent structural changes and phase transitions in polymer materials, biological objects, and other samples.

Obtaining Highly Selective Responses from a Bulk Tin Oxide Gas Sensor

Abstract: Generic gas sensors are commonly used for the detection of different airborne contaminants due to their high sensitivity, long life and low cost, but they generally suffer from the variety of drifts and the lack of selectivity. Different techniques have been developed for selectivity enhancement in metal oxide gas sensors, among which operating temperature modulation is well known. It has been observed that sharp pallet temperature changes provide more analyte-related information. Due to the high thermal capacitance of the device, applying step voltage pulses to a bulk tin oxide gas sensor fails to provide step pallet temperature variations. On the other hand, the low thermal capacity of the custom made microheater gas sensors renders them vulnerable to all kinds of thermal noise and agitations. A novel technique is reported for temperature modulation, which facilitates sharp temperature rises of the gas sensitive pallets in generic gas sensors [. In this technique, a sharp heating voltage spike, considerably surpassing the nominal heating voltage, is applied prior to each heating voltage step. The thermal impact of these spikes is adjusted by controlling v2dt for obtaining the closest variations to the ideal temperature profile. Here, the advantages and effectiveness of the technique are demonstrated by differentiating among iso-butanol, tert-butanol, 1-butanol and 2-butanol contaminations in a wide concentration range in air using only a single generic tin oxide gas sensor.

SOI-based micro-hotplate microcalorimeter gas sensor with integrated BiCMOS transducer

Abstract: In this paper we describe the design of a smart calorimetric solid-state gas sensor based on SOI technology and featuring a thin membrane realised through post-process back etching. Micro-heaters are produced from active CMOS elements (i.e. n- or p-channel MOSFETs) and isolated in a thin SOI membrane in order to permit high temperature operation (up to ca. 300 degreesC). Thermodiodes are placed on and off the micro-hotplates to measure operating and ambient temperatures. The device can be operated as a microcalorimeter when one microheater is coated with an active catalytic layer and the other with an inert material. The differential signal is then simply related to the concentration of a combustible gas in air. Full simulations of the I-V device characteristics; temperature of the membrane and transducer circuit have been carried out. The device has been fabricated at IMEC (via Europractice) employing 0.8 mum TEMIC Matra MHS D-MILL BiCMOS technology. These smart sensors feature very low power consumption, high sensitivity and low fabrication cost achieved through full CMOS integration.

Pyro-Electro-Thermal Analysis of LiNbO3 using Microheaters

Abstract: Microheaters have been widely investigated for their sensor-based applications, such as gas sensor, flow rate sensor and other microsystems. Here, we investigate the pyroelectric effect, activate by microheaters fabricated on -Z surface of LiNbO3 crystal. Pyroelectric effect is the capability of certain crystal to produce temporary voltage during heating or cooling transient. Fabrication of microheaters on LiNbO3 crystals gives an advantage of confined temperature gradient, together with low power consumption for application-based sensors. In this paper, we study the electron emission from the -Z surface of a pyroelectric material (LiNbO3), relevant to the microheaters fabricated on the +Z surface of crystal. Different geometries of microheaters, such as Fan, Meander, Double Spiral and S- Shape were fabricated on +Z surface of a single domain LiNbO3 crystal. Thermal behavior of these microheaters was analyzed using COMSOL™ Multiphysics and compared with the experimental data obtained by FLIR SC7000 Series thermo camera. Static and time-dependent thermal analyses were performed using a voltage generator by applying DC and step voltage signals to the microheater. It was observed that the electric field resulting from the temperature induced by the microheater changes the spontaneous polarization of the LiNbO3 crystal affecting the electron emission. This pyroelectric electron emission (PEE) from -Z surface of the LiNbO3 crystal was investigated using two-probe point measurement. It was observed that the PEE from LiNbO3 is due to the perturbation, by the temperature variation, of equilibrium between spontaneous polarizations Ps in the crystal and external screening charges (qsc) on its surfaces. At equilibrium, all Ps are fully screened by qsc and no external electric field exists. Any excess or lack of screening charges (qsc) relatively to Ps, leads to the appearance of an electrostatic state from the uncompensated charges (ρ) given by ρ = Δ (Ps- qsc). Furthermore, we verified the pyroelectric emission effect in a transient condition for all the microheaters. A voltage signal at 10mHz was applied to the microheater using signal generator. A tip (diameter~0.254mm) was positioned at distance  1mm from the -Z surface of LiNbO3 crystal. The current peaks were acquired using oscilloscope that occurs due to the non-distribution of Ps on the -Z surface of LiNbO3. It was observed that microheaters with complex structure have significantly higher number of current peaks compared to a simplest structure, because complex microheater leads to a nonuniform temperature gradient on the -Z surface of the LiNbO3 crystal. It was also noted that the temporal distances between adjacent electrical peaks exponentially increases during the application of the thermal transient, showing a dependency of the rate of heating and cooling on the PEE in a transient condition of the crystal. Finally, we demonstrate two pyroelectric effect based applications: Pyro-jetting of liquid droplet (oil, OIR 906, water and PDMS) and pyro-emission lithography using microheater.