The bimaterial cantilever beam is an important basic structure of microelectromechanical system thermal devices. The research described in this paper is a study of the deflection of the bimaterial cantilever beam operated in the air and irradiated with a laser beam at the free end. The bimaterial cantilever beam is a composite structure formed by layers of silicon nitride and gold. The temperature variations produce the deflection of the cantilever beam end due to different values of the thermal expansion coefficients of silicon nitride and gold. The deflection was experimentally measured in vacuum and atmospheric pressure when a laser beam was irradiated at the free end. A formula for the calculation of the deflection as a function of incident power applied at the free end of the cantilever beam operated in air was also demonstrated. The predicted values of the deflection calculated using this formula and the experimental values of the deflection were compared, and the results were in good agreement. A systematic investigation of the cantilever beam deflection in vacuum and atmospheric pressure as a function of the heat applied at the free end is important for chemical and biological applications.

This review presents two types of cantilever beams employed as highly sensitive temperature sensors. One type is fabricated from composite materials and is operated in the deflection mode. The second type, used as a temperature sensor and presented in this review, is a resonant cantilever beam. The materials used for the fabrication of the bimaterial cantilever beam are silicon or silicon nitride and thin metallic films such as gold or aluminum. When the temperature changes, the different coefficients of thermal expansion of the metal and silicon cause the sensor to deflect. Considering the models of temperature measurement for biological cells, the heat should be applied locally at the tip of the cantilever beam. Formulas for the calculation of the deflection as a function of incident power applied at the free end of the cantilever beam operated in a liquid are presented in this review. The natural convective heat transfer coefficient was estimated by using the mathematical model and experimental values. For biological applications, the cantilever beam temperature sensor was operated in a liquid, and the heat transfer coefficients were between 381 and 642 W/m²K when the temperature applied to the cantilever's free end varied from 28 to 71.8 °C. The resonant cantilever beam was also demonstrated as a sensitive temperature sensor for biological applications. As a thermogenic sample, brown fat cells (BFCs), which are related to metabolic heat production, are employed. The working principle of the resonator cantilever beam temperature sensor is based on the shift in resonant frequency in response to temperature changes. The resonant frequency and the temperature coefficient were 960 kHz and 22.0 ppm/K, respectively. The measurements were performed by stimulating the activity of BFCs by flowing a norepinephrine (NE) solution (1 µM).

This paper presents processes for glass micromachining, including sandblast, wet etching, reactive ion etching (RIE), and glass reflow techniques. The advantages as well as disadvantages of each method are presented and discussed in light of the experiments. Sandblast and wet etching techniques are simple processes but face difficulties in small and high-aspect-ratio structures. A sandblasted 2 cm × 2 cm Tempax glass wafer with an etching depth of approximately 150 µm is demonstrated. The Tempax glass structure with an etching depth and sides of approximately 20 μm was observed via the wet etching process. The most important aspect of this work was to develop RIE and glass reflow techniques. The current challenges of these methods are addressed here. Deep Tempax glass pillars having a smooth surface, vertical shapes, and a high aspect ratio of 10 with 1-μm-diameter glass pillars, a 2-μm pitch, and a 10-μm etched depth were achieved via the RIE technique. Through-silicon wafer interconnects, embedded inside the Tempax glass, are successfully demonstrated via the glass reflow technique. Glass reflow into large cavities (larger than 100 μm), a micro-trench (0.8-μm wide trench), and a micro-capillary (1-μm diameter) are investigated. An additional optimization of process flow was performed for glass penetration into micro-scale patterns.

Micro-electromechanical systems (MEMS) magnetic sensing at high temperatures over 573 K has not been achieved due to the difficulty in designing the rational interface with strong coupling. Here, a magnetic sensor based on FeGa/single-crystal diamond (SCD) MEMS resonator is realized to circumvent the challenges in magnetic sensing. The present magnetic sensor exhibits a stable high-sensitivity of 7.3 Hz/mT at 573 K and an experimental noise level of ~4nT/√Hz. The performance exceeds those of reported high-temperature magnetic sensors. This work offers a strategy for developing magnetic sensors with merits super to the existing ones. GRAPHICAL ABSTRACT IMPACT STATEMENT The first high-temperature MEMS magnetic sensor over 573 K super to the present ones is realized by coupling a magneto-strictive FeGa film with a diamond MEMS resonator.

The microfabrication with a magnetostrictive Tb_xDy_(1−x)Fe_y thin film for magnetic microactuators is developed, and the magnetic and magnetostrictive actuation performances of the deposited thin film are evaluated. The magnetostrictive thin film of Tb_xDy_(1−x)Fe_y is deposited on a metal seed layer by electrodeposition using a potentiostat in an aqueous solution. Bi-material cantilever structures with the Tb_0.36Dy_0.64Fe_1.9 thin-film are fabricated using microfabrication, and the magnetic actuation performances are evaluated under the application of a magnetic field. The actuators show large magnetostriction coefficients of approximately 1250 ppm at a magnetic field of 11000 Oe.