Fast response frost-dew point hygrometer

Jury, Stanley H.; Kim, Young W.; Bosanquet, Louis P.

doi:10.1021/ac60252a049

Cited by 6 publications

(6 citation statements)

References 2 publications

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“…159 In 1967, a fully automated dew/frost point hygrometer based on a mirror with much better performance was developed with much faster response. 160 In 1978, a solid-state moisture sensor based on porous anodic aluminum oxide was developed with fast response and wide measurement range (−110 C to +50 C). 161 In following two sections, we will review the mirror-based hygrometers and solid-based moisture sensors.…”

Section: Absolute Humidity Sensors (Hygrometers)mentioning

confidence: 99%

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Humidity Sensors: A Review of Materials and Mechanisms

Chen¹,

Lu²

2005

Sen Lett

1,328

708

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We have reviewed humidity sensors based on various materials for both relative and absolute humidity, including ceramic, semiconducting, and polymer materials. In the majority of publications, there are few papers dealing with absolute humidity sensors, which have extensive applications in industry. We reviewed extensively absolute humidity sensors in this article, which is unique comparing with other reviews of humidity sensors. The electrical properties of humidity sensors such as sensitivity, response time, and stability have been described in details for various materials and a considerable part of the review is focused on the sensing mechanisms. In addition, preparation and characterization of sensing materials are also described. For absolute humidity sensors, mirrorbased dew-point sensors and solid-state Al 2 O 3 moisture sensors have been described. As the major problem in Al 2 O 3 moisture sensors, long-term instability, has been solved, -Al 2 O 3 moisture sensors may have promising future in industry.

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Section: Absolute Humidity Sensors (Hygrometers)mentioning

confidence: 99%

“…160 Light from the Farmer electric lamp is projected onto the sensing element and is received by the photo resistor. If water condenses on the gold mirror of the sensing element, the photo resistor picks up the optical signal and the corresponding temperature is recorded.…”

Section: Mirror-based Dew/frost Point Sensors (Hygrometers)mentioning

confidence: 99%

Humidity Sensors: A Review of Materials and Mechanisms

Chen¹,

Lu²

2005

Sen Lett

1,328

708

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“…[3,4] Therefore, the development of technologies or products that can accurately detect and indicate ultralow (<100 ppm) or extremely low (<1 ppm) humidity is of great practical significance.Currently, only semiconductor capacitive sensors based on special crystal forms (i.e., γ-Al 2 O 3 ) and mirror-based dew point hygrometers can achieve accurate detection of ultralow or trace amounts of moisture, with thresholds of 1 ppm and −100 °C of dew point (i.e., 0.01 ppm), respectively. [5,6] However, owing to the complex and harsh manufacturing of core materials and the extremely high requirements for instrument components (such as high-quality mirror surfaces, high-precision temperature control systems and high-sensitivity dewdrop and ice crystal optical detection systems), these instruments are bulky, extremely expensive and require complex external power supply systems or coupling circuits, significantly limiting their widespread application. As an alternative, color-visualized waterresponsive materials offer a simple, low-cost, portable and easy-to-read method for humidity sensing and detection.…”

mentioning

confidence: 99%

“Enzyme‐Like” Spatially Fixed Polyhydroxyl Microenvironment‐Activated Hydrochromic Molecular Switching for Naked Eye Detection of ppm Level Humidity

2022

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To avoid affecting the highly efficient photoelectric conversion of the solar cells, the moisture content of the production workshop should be less than 1 ppm. The preparation of lithium-ion batteries, organic light-emitting devices, optical fibers, and supercapacitors requires humidity conditions of <0.1 ppm. In addition, power transmission (which requires insulating/ anhydrous gas), aviation exploration, and scientific research involve monitoring/ identifying the trace levels of moisture. [3,4] Therefore, the development of technologies or products that can accurately detect and indicate ultralow (<100 ppm) or extremely low (<1 ppm) humidity is of great practical significance.Currently, only semiconductor capacitive sensors based on special crystal forms (i.e., γ-Al 2 O 3 ) and mirror-based dew point hygrometers can achieve accurate detection of ultralow or trace amounts of moisture, with thresholds of 1 ppm and −100 °C of dew point (i.e., 0.01 ppm), respectively. [5,6] However, owing to the complex and harsh manufacturing of core materials and the extremely high requirements for instrument components (such as high-quality mirror surfaces, high-precision temperature control systems and high-sensitivity dewdrop and ice crystal optical detection systems), these instruments are bulky, extremely expensive and require complex external power supply systems or coupling circuits, significantly limiting their widespread application. As an alternative, color-visualized waterresponsive materials offer a simple, low-cost, portable and easy-to-read method for humidity sensing and detection. They provide a direct visual way to convert environmental water vapor stimuli into a naked eye readout color by incorporating humidity-responsive chromic components into a solid support, and the resulting visual humidity sensor can be adapted to different environmental conditions. Thus far, various novel systems/strategies have been developed for visual humidity sensors, including inorganic materials (e.g., cobalt/nickel halides, [7,8] perovskites, [9] and nanocrystals [10] ), photonic bandgap structure materials, [11][12][13][14][15] aggregation discoloration dyes, [16][17][18][19] metal dynamic coordination systems, [20] polaritysensitive fluorescent materials, [21] redox [22] and acid-base [23] color-changing dye switches. These efforts have significantlyThe detection and monitoring of ultralow humidity (<100 ppm) are critical in many important industries, such as high-tech manufacturing, scientific research, and aerospace. However, the development of ppm level humidity sensors with portability, low cost, and ease of regeneration remains a significant challenge. Herein, an innovative "enzyme-like" construction strategy is proposed to address this problem by employing suitable molecular-level humidity-sensitive units and chemically constructing a multilevel spatial synergistic sensitization microenvironment around it. The as-prepared ultralow humidity-sensitive paper (UHSP) achieved a naked eye recognition humidity of 0.01-100 ppm....

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“…A C C E P T E D ACCEPTED MANUSCRIPT 6 There are only a few analytical instruments that can be used for trace water detection [18], including chilled mirror hygrometers [19], thin alumina film capacitive sensors [20], amperometric P 2 O 5 film sensor [21], Fourier transform-infrared spectrometers [22], atmospheric pressure ionization mass spectrometers [23], and cavity ring down spectrometers (CRDS) [24,25]. These instruments are commercially available and perform well [26,27].…”

Section: A N U S C R I P Tmentioning

confidence: 99%