A capacitive humidity sensor integrated with micro heater and ring oscillator circuit fabricated by CMOS–MEMS technique

Dai, Ching‐Liang

doi:10.1016/j.snb.2006.05.042

Cited by 134 publications

(90 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Polymers are appealing because they exhibit long-term stability, are sensitive to high humidity, have low manufacturing costs, and can be easily included in an integrated circuit (IC) process. 16,17 A polymer material that has high thermal stability and low dielectric constant is preferable. 16 Polyimide has superior characteristics such as high temperature resistance, a low dielectric constant, good mechanical strength, and dimensional stability, and is typically the material of choice for a capacitive humidity sensor's dielectric, due to its higher affinity toward moisture absorption and desorption.…”

Section: Compliant and Biocompatible Plant Sensorsmentioning

confidence: 99%

Compliant plant wearables for localized microclimate and plant growth monitoring

et al. 2018

View full text Add to dashboard Cite

The microclimate surrounding a plant has major effect on its health and photosynthesis process, where certain plants struggle in suboptimal environmental conditions and unbalanced levels of humidity and temperature. The ability to remotely track and correlate the effect of local environmental conditions on the healthy growth of plants can have great impact for increasing survival rate of plants and augmenting agriculture output. This necessitates the widespread distribution of lightweight sensory devices on the surface of each plant. Using flexible and biocompatible materials coupled with a smart compact design for a low power and lightweight system, we develop widely deployed, autonomous, and compliant wearables for plants. The demonstrated wearables integrate temperature, humidity and strain sensors, and can be intimately deployed on the soft surface of any plant to remotely and continuously evaluate optimal growth settings. This is enabled through simultaneous detection of environmental conditions while quantitatively tracking the growth rate (viz. elongation). Finally, we establish a nature-inspired origami-assembled 3D-printed "PlantCopter", used as a launching platform for our plant wearable to enable widespread microclimate monitoring in large fields.

show abstract

Section: Compliant and Biocompatible Plant Sensorsmentioning

confidence: 99%

Compliant plant wearables for localized microclimate and plant growth monitoring

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In particular, polyimide (PI) has been extensively investigated to be used as a sensing material of the MEMS-based capacitive humidity sensors due to its good linearity, high sensitivity, low hysteresis, high resistance to most chemicals, relative ease of fabrication, and mass producibility. Many researchers have proposed the humidity sensors using a PI sensing film (Dai 2007;Kang and Wise 2000;Gu et al 2004;Kim et al 2009a). However, low performance or complex device structure is still a major limitation in miniaturized humidity sensors for real-life applications.…”

Section: Introductionmentioning

confidence: 99%

High-performance capacitive humidity sensor with novel electrode and polyimide layer based on MEMS technology

et al. 2010

View full text Add to dashboard Cite

A high-performance capacitive humidity sensor based on a newly designed electrode and a polyimide (PI) layer is presented in this paper. The humidity sensor consists of a substrate with a cavity, a bottom electrode, a PI sensing layer, and a comb-shaped top electrode with branches. The cavity structure of the substrate was formed to protect the top electrode. In order to enhance the performance of the sensor, the coated PI layer was etched by using an O 2 plasma asher in accordance with the top electrode passivation. After the PI etching, the humidity sensor showed a high sensitivity of 506 fF/% RH and a fast response time of less than 6 s, which is attributed to the increased contact area between the PI layer and moisture, and shortened moisture absorption path into the PI layer. Further characterizations were carried out to measure the effect of temperature, hysteresis, and stability. The humidity sensor showed a hysteresis of 2.05% RH, little temperature dependence, and stable capacitance value with maximum 0.28% error rate for 24 h.

show abstract

“…The resistive-type sensors are based on a change of the real part of the impedance of the sensing material with a change in the surrounding humidity while the capacitive-type sensors are based on a change of the imaginary part of the impedance. The most common capacitive-type humidity sensors use a dielectric material as the active sensing material included in an interdigitated electrode configuration [7,8]. Absorption of water into the dielectric layer changes its permittivity, thus modulating the capacitance (and the resonance frequency if incorporated into a LC resonance sensor) [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Proton motion in a polyelectrolyte: A probe for wireless humidity sensors

Larsson

Wang

Berggren

et al. 2010

Sensors and Actuators B: Chemical

View full text Add to dashboard Cite

Low-cost passive wireless electronic sensor labels glued onto packages are highly desirable since they enable monitoring of the status of the packages for instance along the logistic chain or while stored at a shelf. Such additional sensing feature would be of great value for many producers and vendors, active in e.g. the food or construction industries. Here, we explore a novel concept for wireless sensing and readout, in which the humidity sensitive ionic motion in a polyelectrolyte membrane is directly translated into a shift of the resonance frequency of a resonance circuit. Thanks to its simplicity, the wireless sensor device itself can be manufactured entirely using common printing techniques and can be integrated into a lowcost passive electronic sensor label.

show abstract

A capacitive humidity sensor integrated with micro heater and ring oscillator circuit fabricated by CMOS–MEMS technique

Cited by 134 publications

References 16 publications

Compliant plant wearables for localized microclimate and plant growth monitoring

Compliant plant wearables for localized microclimate and plant growth monitoring

High-performance capacitive humidity sensor with novel electrode and polyimide layer based on MEMS technology

Proton motion in a polyelectrolyte: A probe for wireless humidity sensors

Contact Info

Product

Resources

About