Humidity sensor technology

Humidity sensor technology has a wide range of applications in medical devices, air conditioners, or ventilators, and mobile devices. Although the number and process of the industry require it, the value of the humidity sensor is more reflected.

Accurate humidity measurement is an important part of controlling humidity in case of damage, discomfort, or to detect this event that may cause product damage during storage or transit. For widespread use, RH sensing must be available in component form to enable easy, cost-effective integration and electronic control.

Technology Measuring Humidity

Humidity can be quantified in many ways, but the most important measure is maintaining air quality relative humidity (RH). This is the amount of water present in the air than the actual water vapor present in the saturated air; it cannot absorb more moisture. Absolute humidity is defined as the mass of water vapor dissolved in a total amount of moist air at a given temperature and pressure.

Electronic Humidity Sensing Technology

Electronic humidity sensors overcome many of the size and cost issues that plagued older technologies. The most commonly used techniques either rely on a changing resistance or capacitively adsorbed material. A capacitive sensor consists of two electrodes, a dielectric material. In general, as the moisture content in the air increases, the permittivity of the sensor increases, changing the measured capacitance to the corresponding humidity level. A resistance sensor consists of two electrodes, a conductive layer. In this case, the change in humidity caused by the change in conductivity of the remote sensing layer.

New technology to make films makes these types of relative humidity sensors accurate, stable, and easy to mass produce. Choose hygroscopic materials to ensure fast response times and small lags. For example, a polyimide film can be fabricated at different thicknesses with a <5 μm change in the reaction and can provide humidity in the <10s while providing excellent stability. The accuracy of an electronic RH sensor is limited by its drift over time, and often large changes are caused by the presence of temperature and humidity or contaminants.

To increase the accuracy of the measurement RH, it is also helpful to measure temperature to provide temperature compensated RH measurement equipment if necessary. To determine the dew point or absolute humidity, air temperature is also required. For example, a 1°C error measurement temperature will produce an approximate 1°C error at the dew point. The best accuracy, humidity, and temperature measurements should be as close to each other as possible, ideally coexisting on the same chip. This approach is difficult to achieve with many traditional electronic sensor designs.

Many of today's electronic sensor designs use discrete resistance and capacitive sensors, hybrid vehicles, and multichip modules (reverse minecraft), as shown in Figure 3. These legacy methods suffer from high BOM costs and component counts. Large footprints require labor-intensive customer calibration. Another problem is that discrete sensor solutions often do not conform to standard Surface Assembly Technology (SMT) assembly flows.