Fabrication and characterization of a piezoresistive humidity sensor with a stress-free package

Waber, T.; Sax, Markus; Pahl, W.; Stufler, S.; Leidl, Anton; Guenther, Margarita; Feiertag, G.

doi:10.5194/jsss-3-167-2014

Cited by 7 publications

(4 citation statements)

References 16 publications

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“…Therefore, various MEMS technologies have also been investigated and developed to design and fabricate micro humidity sensors. The sensing mechanisms include resistive type [111][112][113], capacitive type [88,109,[114][115][116][117][118][119][120][121][122][123][124], piezo-resistive type [125] and resonance type [126,127], etc. This section will review the CMOS-MEMS humidity sensors and their monolithic integration with thermometer as well.…”

Section: Humidity Sensor and Temperature Sensormentioning

confidence: 99%

“…By exploiting the existing BEOL thin film layers of the CMOS processes and design rules of the CMOS processes, different sensing electrodes can be designed and fabricated using post-CMOS processes, and then the water vapor sensing materials can be filled into the sensing electrodes. Generally speaking, the design concerns for humidity sensors may include the response time, and sensitivity [109,[111][112][113][114][115][116][117][118][119][120][121][122][123][124][125][126][127], etc. The response time indicates how fast the sensor can detect two different humidity levels.…”

Section: Capacitivementioning

confidence: 99%

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CMOS-MEMS technologies for the applications of environment sensors and environment sensing hubs

Lee

Hsieh

Lin

et al. 2021

J. Micromech. Microeng.

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The booming growth in environmental conditions sensing and monitoring pushes the need of inexpensive environment sensors with small size and low power consumption. The outbreak of COVID-19 further increases the need for fast monitoring of environment conditions. The micro-electrical-mechanical-systems (MEMS) technologies are considered as promising solutions to realize the required environment sensors. The mature complementary metal-oxide-semiconductor (CMOS) process platforms available in many foundries can be extended to fabricate MEMS sensors to offer the advantage of relatively easier commercialization. Moreover, by leveraging the characteristics of CMOS process platforms, the integration of multiple sensors and sensing circuits to form a compact sensing system can also be achieved. This review paper will focus on introducing the miniaturized environmental sensing devices implemented and integrated using the CMOS-MEMS technologies. In general, the CMOS chips for environment sensing are firstly fabricated using the foundry-available CMOS processes, and then the post-CMOS micromachining processes are performed to implement the CMOS-MEMS environment sensors. This paper respectively reviews five different environment sensors (including the infrared, pressure (barometer), humidity/temperature, and gas sensors) using the CMOS-based MEMS technologies. The advantages and design concerns of sensors fabricated by different CMOS and post-CMOS processes are introduced and discussed. Moreover, the CMOS-MEMS environment sensing hub implemented through the monolithic integration of multiple environment sensors is also introduced.

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Section: Humidity Sensor and Temperature Sensormentioning

confidence: 99%

Section: Capacitivementioning

confidence: 99%

CMOS-MEMS technologies for the applications of environment sensors and environment sensing hubs

Lee

Hsieh

Lin

et al. 2021

J. Micromech. Microeng.

View full text Add to dashboard Cite

show abstract

“…Recently, miniaturized sensors for portable devices such as mobile phones are available, including the following: SHTC1 humidity sensor from Sensirion and LPS331AP pressure sensor from STMicroelectronics are being used in Samsung cell phones; Bosch Sensortec company introduced a miniaturized humidity sensor capable of sensing pressure and temperature (BME280), which are based on Micro-Electro Mechanical Systems (MEMS) [ 27 ]. Although the power consumption for these sensors is very small because of their microsize, proportionally, their sensing capacity is also very small, leading to a high signal-to-noise ratio, which requires amplification; likewise, parametric amplification may also be required [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers

et al. 2021

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Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO–CuO–MWCNT: 1%, and PEO–CuO–MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz–1MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30–90%. More specifically, the PEO–CuO–MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO–CuO–MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.

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“…The latter devices take advantage of the bending of the cantilever beam due to stress caused by the adsorption of molecules on the functional layer, and the bending is monitored by optical detection methods. Although these sensors can detect target materials in a picogram range, the practical applications are limited by the bulky size of the optical measurement system and the necessity to align a laser toward each cantilever [11]- [13]. A promising alternative that may overcome these problems is a self-sensing method based on a piezoresistive strain sensor.…”

Section: Introductionmentioning

confidence: 99%

Piezoresistive Nanomechanical Humidity Sensors Using Internal Stress In-Plane of Si-Polymer Composite Membranes

et al. 2019

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This article presents the design and fabrication process of a highly miniaturized nanomechanical Si-polymer composite membrane-type internal-stress sensor (MIS) with piezoresistive elements for humidity detection. The 500-μm 2 area dimension sensor consists of a thin Si-polymer composite membrane supported by two piezoresistive Si beams. The composite membrane is fabricated as follows: First, 1-μm-wide width Si slits with 1 μm separation gaps are formed by using photolithography and deep reactive-ion etching, and then, the Si slits are filled with a functional polymer (methyl methacrylate based acrylate resin: OLESTER TM Q155). This composite device acts as an absorber of vapor molecules and, consequently, generates stress. The fabricated sensor in a humidity-controlled chamber shows a relative resistance change R/R device = 0.6% for 58% relative humidity (RH) change and a highly linear steady response of 5.2 mV/%RH up to 70% RH change with sensing resolution of 0.5% humidity. The measured polymer expansion ratio of ϵ p = 2.4 × 10 −3 is consistent with the theoretical estimation using the weight fraction of water adsorbed in the polymer.

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Fabrication and characterization of a piezoresistive humidity sensor with a stress-free package

Cited by 7 publications

References 16 publications

CMOS-MEMS technologies for the applications of environment sensors and environment sensing hubs

CMOS-MEMS technologies for the applications of environment sensors and environment sensing hubs

Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers

Piezoresistive Nanomechanical Humidity Sensors Using Internal Stress In-Plane of Si-Polymer Composite Membranes

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