Formaldehyde passive sampler using an optical chemical sensor: how to limit the humidity interference

Evaluation of a passive air sampler for measuring indoor formaldehyde.

A passive air sampler, using 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, was evaluated for the determination of formaldehyde in indoor environments. Chromatography paper cleaned using a 3% hydrogen peroxide solution was experimentally determined as being the optimum absorption filter for the collection of formaldehyde (0.05 microg cm(-2) formaldehyde). From a linear-regression analysis betwe...

Humidity Sensor Using an Air Capacitor

We studied the possibility that an air capacitor can be used as a humidity sensor by measuring capacitance change. In order to investigate the possibility, the change of capacitance of an air capacitor due to moisture in air was first considered theoretically, and was then experimentally verified. The capacitance was measured by an LCR impedance meter with a 100-kHz and 1-V ac. The results reve...

Esa Based Fiber Optical Humidity Sensor

An Integrated Optical-Holographic Chemical-Vapor Sensor

This thesis addresses the problem of chemical vapor detection by using an integrated opticalholographic interferometer for precision interrogation of a chemical transducer. A monolithic-prism interferometer, incorporating dynamic holography in conjunction with a “sniff-locked-loop” sampling scheme, achieves high sensitivity at high speed while mitigating the deleterious effects of environmental...

A Novel Passive Wireless Sensor for Concrete Humidity Monitoring

This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigit...