A sensor is an instrument which reacts to certain physical conditions or impressions such as heat, light, sound, pressure, and magnetism. It is used to provide information by converting external various signals into electrical signals. At present, countries around the world attach great importance to the development of sensor technology. Ionic liquids have good solvation property, non-volatility, high ion density, high ionic conductivity, low toxicity, large electrochemical window (i.e the electrochemical potential range over which the electrolyte is neither reduced nor oxidized on electrodes) and good electrochemical stability, so they are suitable for a variety of sensor applications, such as strain sensors, temperature sensors, gas sensors, humidity sensors, and pressure sensors.
Ionic liquids have interesting characteristics that make them suitable for the fabricate of various types of sensors. Some examples of ionic liquids used in sensor research are shown below.
The sensing mechanism of strain sensors is that the resistance or capacitance of the sensor changes when the sensor is subjected to external stress, and through the change of these parameters, the external stress or strain can be detected. The selection of conductive materials is essential to improve the performance of strain sensors. Compared with conventional solid electronic materials, ionic liquids are usually in liquid form at room temperature, and their dissipative modulus is much greater than that of storage modulus. When external stress is applied to ionic liquids, strain is almost the only way to dissipate stress, which provides a theoretical support for the construction of ultra-sensitive strain sensors based on ionic liquids. To date, many ionic liquid-based strain sensors with excellent characteristics such as high sensitivity, large strain range, fast response time, good stability and repeatability have been developed. They have diverse potential applications, such as human motion detection, prostheses, personal health monitoring, soft robotics, and smart clothes.
Figure 1. Schematic illustration of the fabrication process of the ionic liquid-based strain sensor .
The resistance of ionic liquids decreases with increasing temperature, which is consistent with the behavior of conventional solid semiconductors. However, the carriers of ionic liquids are anions and cations, so their temperature-sensitive behavior follows a different mechanism from that of conventional solid semiconductors. As temperature increases, the viscosity and aggregation behavior of ionic liquids are weakened, which increases the concentration of free carriers in the system and reduces the resistance of carrier migration, so that the conductivity of ionic liquids increases gradually with the increase of temperature . Given the unique properties of ionic liquids and the temperature-sensitive behavior of ionic liquids, many researchers have developed a series of ionic liquid-based temperature sensors. In addition to sensitive temperature response function, these sensors also have the superiority of flexibility, self-repairability and remoldability.
In addition to the sensors mentioned above, Alfa Chemistry can also provide ionic liquids for other types of sensor research, such as gas sensors, near-infrared light sensors and humidity sensors.
Sensor technology plays an important role in developing economy and promoting social progress. The key to obtain a sensor with excellent comprehensive performance is the selection of conductive materials. Ionic liquids not only have high ion density and high ionic conductivity, but also have the advantages of environmental friendliness, recyclability and non-flammability, which is expected to avoid environmental hazards caused by the disposal of electronic products and in line with the development trend of current green electronic technology. With in-depth knowledge of sensors theory and advanced ionic liquid technology, Alfa chemistry has the ability to provide effective solutions to a variety of problems encountered in the application of ionic liquids in sensors.
Alfa Chemistry believes that ionic liquids will greatly promote the development of sensor technology. We will be pleased to offer our customers a range of solutions to meet the challenges of ionic liquids in sensors research. If you have any questions related to sensor research, please feel free to contact us.
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