Cantilever beam temperature sensors for biological applications

Abstract

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/m 2 K 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).

Nano and Microsensors for Mammalian Cell Studies

“…One is the vibration mode, which measures resonant frequency changes due to additional mass at the apex of the cantilever beam. For the vibration mode, the cantilever beam is considered as a simple spring with an effective mass connected to the free end ( Figure 2 a) [ 83 ]. The second operation mode of the cantilever beam is the bending mode, which measures the static deflection of the cantilever beam.…”

Modeling of an Optically Heated MEMS-Based Micromechanical Bimaterial Sensor for Heat Capacitance Measurements of Single Biological Cells

“…Because of the ultrasensitivity of BMCs, they have been used as sensing platforms in many applications [32,33]. Toda et al reported a highly sensitive bimaterial microcantilever temperature sensor [34]. They successfully detected, in situ, the local heat generated by a single mammalian cell.…”

Design and Electro-Thermo-Mechanical Behavior Analysis of Au/Si3N4 Bimorph Microcantilevers for Static Mode Sensing

“…In microcantilever-based MEMS sensors, monitoring mechanical deflections (i.e., static mode sensing) in thermal response to changes in temperature has frequently been adopted as the sensing mechanism. For instance, the changes in surface temperature of the microcantilever can be induced by surface catalytic reactions [ 2 , 7 ] or infrared (IR) absorption [ 8 ]. On the other hand, changes in the resonant frequency upon mass uptake are monitored in the dynamic mode [ 9 ].…”

“…Bimorph structures, which consist of a semiconductor material (e.g., silicon, silicon nitride) and a metal (e.g., aluminum, gold), have the ability to exhibit higher sensitivity in the detection of very small changes in temperature than monomaterial microcantilevers [ 8 ]. In particular, the thermal actuation caused by temperature changes relies on the mismatch in coefficients of thermal expansion (otherwise known as the bimetallic effect) between two different types of materials.…”