A relative humidity sensitive material comprises a mixture of at least one hygroscopic salt and an at least partially electrically conductive metal based powder. Each salt in the relative humidity sensitive material has a cationic constituent selected from the group consisting of the alkali and alkaline earth metals and an anionic constituent selected from the group consisting of a chlorate, perchlorate, and chloro aluminate. The metal based powder preferably comprises a metal or metal oxide powder or powder mixture including such constituents as Zr, CO.sub.3 O.sub.4, and MnO.sub.2. Additionally, the material may include a binding agent and a slurry mixture may be formed for placement of the resultant material between electrodes on a substrate so as to form a relative humidity sensor. These sensors are employed either individually or configured in a system used to either indicate or control the relative humidity.
A humidity-sensing component composition includes a metallic oxide and a chalcogen oxyacid salt represented by a general formula A.sub.x B.sub.y O.sub.z where A is one of an alkali metal and an alkaline earth metal, B is one of sulphur, selenium, and tellurium, O is oxygen, x is 1 to 2, y 1 to 5, and z 2 to 7. The chalcogen oxyacid salt is blended by an amount of 0.01 to 99.99 mol % in the metallic oxide with the sum of the metallic oxide and the chalcogen oxyacid salt as a reference. The metallic oxide and the chalcogen oxyacid salt are sintered under an atmosphere of molecular oxygen.
A moisture and dew-detection sensor comprises a fabric and a moisture sensing resistive substance adhered in a substantially continued and dispersed state to the fabric, and a plurality of fine voids are formed in the moisture and dew-detection sensor. A response time and an accuracy of the sensor in accordance with the present invention are superior due to the existence of the plurality of voids.
A humidity sensor to detect humidity by utilizing a change in the electric characteristics of the device corresponding to a change in the humidity. A solution containing manganese acetate, lead acetate and potassium acetate is coated on an alumina substrate on which interdigital electrodes are formed, and heat-treatment is carried out to provide a humidity sensor having a humidity sensing film which mainly contains manganese oxide, lead oxide and a compound of the alkali metal. The humidity sensor shows a low impedance and an appropriate dynamic range of the impedance even after being downsized. The humidity sensor shows a quick response and excellent environmental resistance. In addition, the humidity sensor and a humidity measuring circuit are easily produced. Thus, the humidity sensor can be widely used in those fields that require a humidity sensor of a small size, a quick response, high reliability and a low cost such as in portable instruments and the like.
A humidity sensitive device, including opposing electrodes formed on an insulating substrate, and a humidity sensitive film formed on the surface of the insulating substrate and at least between the opposing electrodes. The humidity sensitive film is obtained by coating on the surface of the insulating substrate a mixture including a conductive or semiconductive powder, a solid electrolyte powder and an organic polymer cross-linked by a zirconium compound and heating the same.
A humidity sensor formed of a sintered compact consisting essentially of material substantially of a spinel structure represented by the formula: M.sub.1-x A.sub.x Fe.sub.2 O.sub.4-.alpha. where M stands for magnesium or zinc, A stands for an alkali metal, x is the numerical value in the range of 0.001 to 0.2, and .alpha. is the number of oxygen vacancies. The humidity sensor is highly sensitive over a wide relative humidity range, withstands a long use and presents almost no hysteresis in its humidity-resistance characteristics.
