A Surface Micromachined CMOS MEMS Humidity Sensor

Featured Application: Three-axis magnetic field microsensors in this study can be applied to various electronic instruments, portable electronic devices, mobile phones, and industrial equipment.Abstract: This study develops a three-axis magnetic field (MF) microsensor manufactured by a complementary metal oxide semiconductor (CMOS) process. The MF microsensor contains a ring emitter, four bases, and eight collectors. Sentaurus TCAD was used to simulate the microsensor characterization. The STI (shallow trench isolation) oxide in the process was used to limit the current direction and reduce leakage current. The microsensor produces a voltage difference once it senses a magnetic field. An amplifier circuitry magnifies voltage difference into a voltage output. Experiments reveals that the MF microsensor has a sensitivity of 1.45 V/T along the x-axis and a sensitivity of 1.37 V/T along the y-axis.

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“…Many microsensors have been made this way [23][24][25]. In this study, a 3-axis MF microsensor was developed using the CMOS-MEMS technique.…”

Section: Introductionmentioning

confidence: 99%

A Three-Axis Magnetic Field Microsensor Fabricated Utilizing a CMOS Process

et al. 2017

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“…Several composites have been investigated in the literature, such as polyaniline and tungsten oxide (PANI/WO 3 ), TiO 2 nanoparticle/polypyrrole, iron oxide-polypyrrole (Fe 3 O 4 -PPY) nanocomposite, etc. These hybrid sensors have shown high performance behaviors in response time, mechanical strength, and hysteresis features [37][38][39].…”

Section: Standard Resistive Humidity Sensorsmentioning

confidence: 99%

MEMS Humidity Sensors

Alfaifi¹,

Zaman²,

Alsolami³

2023

Humidity Sensors - Types and Applications

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This chapter reviews MEMS humidity sensors fabricated using microfabrication technologies. It discusses the operation principle, different designs, and the fabrication technologies for the different sensing mechanisms. Sensing humidity using capacitive sensors is first reviewed with a highlight on the different sensing materials and how their permittivity and physical parameters affect the sensor performance. Then the chapter discusses the piezoelectric humidity sensing method, wherein piezoelectric sensors the dynamic mode measurement is used. In these sensors, the mass changes corresponding to the humidity, resulting in resonance frequency shift and amplitude change. Finally, the chapter reviews the resistive humidity sensors where the change in the resistivity of various materials is used as an indication of humidity change in the environment.

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“…To prove this concept, in this work here a simple macro device is considered where both the pre-stress and the pre-deflection are applied by a screw acting axially on an elastically suspended bending beam coated with a humidity-sensitive hydrogel layer. Figure 1 shows the general setup and working principle of MEMS-based moisture threshold switches (Huang et al, 2015;Dai et al, 2013). The silicon-based bending plate with Published by Copernicus Publications on behalf of the AMA Association for Sensor Technology.…”

Section: Motivationmentioning

confidence: 99%

Modelling and model verification of an autonomous threshold sensor for humidity measurements

Gulnizkij

Gerlach

2020

J. Sens. Sens. Syst.

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Abstract. Autonomous sensors that receive their energy from an energy harvester or directly from the environment have the potential to save energy for applications in numerous sectors. For humidity sensing, the swelling behaviour of a water vapour-sensitive hydrogel is used. To trigger an electrical contact the mechanical energy is taken from the hydrogel swelling by the bimorph effect. As long as a defined threshold is not reached, the electrical microcontact remains open. By passing the threshold value, a switching will be triggered causing the closure of the contact. This sensor principle does not need any electrical power supply because the switching power is provided directly by the surrounding humidity as quantity to be measured. For the description of the deflection versus the hydrogel pattern of such a sensor, a model was developed by means of the beam theory. Goal of the model was to derive design guidelines for the dimensioning of the sensors bending plate and the patterned hydrogel layer. Experiments then should show the applicability of the model approaches. The deflection of the bending plate depends on the ratio between the lengths of the uncoated and the coated part of the bending plate where the maximum occurs at a ratio of ca. 0.5. The swelling behaviour of the hydrogel shows a high sensitivity with regard to slight changes in relative humidity. This can be used for humidity threshold sensors that open and close microcontacts with respect to very small changes in relative humidity. To avoid voltage peaks and arcs during the switching process that could arise and destroy the microcontact, a bistable characteristic with hysteresis is needed. Experiments demonstrate the feasibility of this concept and are in good agreement with the modelling results.

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A Surface Micromachined CMOS MEMS Humidity Sensor

Cited by 18 publications

References 15 publications

A Three-Axis Magnetic Field Microsensor Fabricated Utilizing a CMOS Process

A Three-Axis Magnetic Field Microsensor Fabricated Utilizing a CMOS Process

MEMS Humidity Sensors

Modelling and model verification of an autonomous threshold sensor for humidity measurements

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