ES2329533B2 - PIEZOELECTRIC SHIELD FOR SENSORS USED IN ENVIRONMENTAL APPLICATIONS. - Google Patents

Abstract

Piezo shield for sensors used in environmental applications.

It consists of the deposition of rows of material piezoelectric (2) on the active part (1) of the alternating sensor with rows in which no deposition is made. He insulation of the active part of the sensor (1) is achieved increasing the volume of the piezoelectric material (2), by means of its connection to a continuous power supply (4) through  a switch (3).

Description

Piezo shield for sensors used in environmental applications.

Technical sector

The present invention relates to the development of a piezo shield that can be used to coat multitude of electrochemical type sensors and avoid saturation and corresponding disable of the sensor. These sensors are from immediate application in the environmental sector being used to environmental measures, such as relative humidity, CO2, CO, O2 or hydrocarbons.

Background of the invention

The sensors applied in measurements environmental are usually of the electrochemical type and are made of a material that is sensitive to the substance they want detect. In this way, the sensor gives a voltage signal that It depends on the concentration of the external environment.

A typical example of this type of sensors are those of relative humidity. In this case the sensor has a part active consisting of two condenser plates (one of them permeable) with a polymer-type dielectric inside. He water vapor passes through the permeable plate and increases or decreases the dielectric constant of the capacitor and, therefore, its capacity and voltage signal vary. The existing problem is When the sensor reaches a value close to 100% humidity saturates and becomes useless, so you have to make a recovery treatment on it. Another example of sensors are the ones used for gas detection atmospheric, such as CO 2, CO, O 2 or hydrocarbons Its operating principle is similar, with the except that an active part that is sensitive to gas is sought that you want to detect.

This shield shows a shield piezoelectric to protect this type of saturation sensors caused by an excess of substance in the active part of the sensor.

Description of the invention

The piezoelectric shield for sensors used in environmental applications consists of depositing, on the active part of the sensor, rows of piezoelectric material alternated by rows in which no deposition is made. From In this way, the substance that acts is allowed in the normal state over the sensor reach it through the rows without deposition. When it is desired that the sensor ceases to receive the influence of the substance to which it is sensitive, a voltage is applied on the rows of piezoelectric material, so that it expands, increases volume and prevents contact of the active part of the sensor with the external environment

The main advantage of this invention is that it Very simple sample to avoid sensor saturation electrochemicals that are used in many applications.

Brief description of the drawings

For a better understanding of how much is left described herein, the following are accompanied drawings.

Figure 1 shows the piezo shield without activate (open circuit power supply).

Figure 2 shows the piezo shield activated (closed circuit power supply and dilated piezoelectric).

Description of a preferred embodiment

The proposed piezo shield consists of to deposit, on the active part of the sensor (1), rows of piezoelectric material (2) alternated by areas where it is not Make any deposition. The structure formed is similar to a grating. This can be done without great difficulty using masks and deposition techniques such as those used in microelectronics. The piezo that is proposed to be used is barium quartz or titanate.

The rows of piezoelectric material are connected in parallel, and through a switch (3), to a DC power supply (4). So when the switch (3) is open no voltage is applied on the piezoelectric and the active part of the sensor is in contact with the external environment On the contrary, when the switch (3) is close, the applied voltage causes the volume to increase piezoelectric (2) and isolates the active part of the sensor (1) to Avoid any risk of saturation.

Claims (1)

1. Piezoelectric shield for sensors used in environmental applications, it is essentially characterized by the deposition of rows of piezoelectric material (2) as a grid, so that the active part of the sensor (1) is isolated from the environment when the piezoelectric is connected (2) to a continuous power supply (4).