Application of nano-sensor technology in packaging and printing (5)

3, the application of sensors in paper mills to control pollutants

Environmental monitoring is very important for environmental protection. The traditional monitoring methods have many disadvantages: slow analysis speed, complicated operation, and expensive instruments, which can not perform on-site rapid monitoring and continuous online analysis. The development and application of biosensors provide new means for it. The use of microbial cells in the environment, such as bacteria, yeast, and fungi, serves as a recognition element that can be generally separated from active sludge deposits, river water, rubble, and soil. The most common application of biosensors in environmental monitoring is water quality analysis. For example, special sensors and their accessories can be placed in rivers for on-site monitoring. A typical application is the determination of Biochemical Oxygen Demand (BOD). Traditional methods for measuring BOD take 5 days and the operation is complex. The microbiological sensor of BOD can measure the result in l5min. Many different microbiological BOD sensors and other microbial sensors for water pollution monitoring have been developed at home and abroad, such as detecting heavy metal ion pollutants based on the inhibition of heavy metal ions on microbial metabolism.

4, the application of nano-gas sensor

An important class of sensors is chemical sensors, which are important components of chemical sensors. Gas sensors usually use the change of the composition of the metal oxide with the surrounding gas, resulting in changes in the resistance and so on to detect and quantitatively measure the gas. The smaller the particle size of the gas sensor material, the higher the specific surface area, the greater the interaction between the sensor and the surrounding gas, and the higher the sensitivity. The sensor composed of titanium dioxide, zirconium dioxide, etc. can be used in oxygen, nitrogen and other atmospheres. The forecast. A gas sensor made of a tin oxide film can be used to warn chemical agents in battle areas, flammable gas leaks, and humidity changes.

Another hot spot for chemical sensor applications is energy saving. For example, solid electrolyte sensors, NOx, Sox gas sensors, etc. are widely used in combustion control systems and automobile exhaust gas monitoring. On the one hand, energy can be saved and the environment can be effectively improved. Of these requirements, 80% are gas sensors, so finding special gas-sensitive materials to make sensors is a new driving force for the development of the sensor industry.

Most odor sensors are formed on the basis of gas sensors. Odor sensors can also be used for the identification of tea and wine, especially for the delicate taste changes between them. If the four lipid membranes are not collected digitally, but can reflect the interactions of the odorous substances and are related to the components, and can be taken out by the continuous amount of the solidified semiconductors, the information on the taste can be seen on the semiconductor. For example, the sour taste is red and the taste is blue. This way of output in a visible form fully reflects the success people have achieved in the visual technology of taste. However, for long-term use, this method also has the problem of curing the lipid membrane, so as one of the application examples of the new image sensor in the 21st century, we look forward to its further development.

5, the application of nanosensors in the field of military packaging

The practicality of the optical fiber temperature sensor lies in that its temperature-sensing element does not contain electrical factors, so it has excellent explosion-proof performance. The use of nanomaterials to create skins of aircraft or weapons can be used to perceive very subtle external stimuli. For example, a smart skin made of nanomaterials on an airplane can provide the pilot with the best flight data based on the flight speed. And to ensure that the aircraft's radar signal characteristics to a minimum extent. The principle of the gas sensor is to use the change of metal oxidation with the surrounding gas composition, resulting in changes in the resistance and so on to detect and quantitatively measure the gas. Sensors made with nanoparticles have the advantage that the microparticles usually have only one to several micrometers in size. The smaller the particles, the larger the specific surface area. The greater the interaction between the surface and the surrounding surface, the more sensitive it is. The higher. Sensors made of tin oxide film can be widely used in battlefield chemical alarms, flammable gas leak alarms, and temperature change forecasts. Since quantum devices operate at speeds more than 1000 times faster than semiconductor devices, the use of quantum devices instead of semiconductor devices can greatly improve the ability of information transmission, storage, and processing in aerospace and weaponry control systems. After the application of nanotechnology, radar can not only reduce the volume to 1 ,, thereby improving radar protection and stealth functions, but also can increase the information acquisition capability by several hundred times. Can be used for military protective packaging.

6, freshness sensor for fresh packaging

Biosensors can be widely used in food industry production, such as the detection of food ingredients, semi-finished products and product quality, and online monitoring during fermentation production. The amino acid oxidase sensor can be used to measure various amino acids (including tens amino acids such as glutamic acid, L-aspartic acid, and L-arginine). There are many kinds of food additives, such as sweeteners, sour agents, antioxidants, and so on. Biosensors have been used for the analysis of food additives. Freshness is one of the important indicators for evaluating the quality of foods. People often use human perception tests, but sensory tests have strong subjectivity and individual differences. Therefore, people have been looking for objective physical and chemical indicators to replace them. Volpe et al. used xanthine oxidase as a biosensing material in combination with a hydrogen peroxide electrode to determine the concentrations of inosine monophosphate (IMP), inosine (HXR) and hypoxanthophyll (HX) produced during fish degradation. To evaluate the freshness of fish.

Now, Europe and the United States have used histamine to evaluate freshness. Histamine is a toxin that can cause food poisoning. It may be possible to produce this kind of thing when the fish is released for a long time. In the future, the measurement of the K value and the measurement of histase can be used simultaneously in the measurement to ensure food safety more reliably. Freshness can also be evaluated using an olfactory sensor (gas sensor). The odor of trimethylamine (TMA) in the ammonia series is the same as that of fish when it is not fresh (rancid). So we can try to use TAM oxide semiconductors as measurement sensors. For example, when measured with ruthenium-titanium oxide, its resistance decreases with the degree of deterioration of the fish. Therefore, reduction in the degree of freshness can also be evaluated using the decrease in resistance. It can be used as a fresh-keeping bag for aquatic products.

7. Application in Automotive Transportation Packaging Logistics

(1) Smart Tire Sensors: Germany, Spain and Luxembourg are jointly developing the application of amorphous wire in automobile tires. The goal is to use their GMI effect and Surface Wave Acoustic Wave to realize the remote sensing of tire conditions during operation. Monitor and improve vehicle safety. The key device is a sensor for detecting tire wear and tire pressure. The principle is that the amorphous wire element is coupled to the SAW transceiving device as an external load. The change of the impedance of the amorphous wire caused by the magnetic field or stress changes the resonant frequency of the SAW. Constitute a wireless passive magnetic or force sensitive sensor. If magnetic particles are dispersed in a rubber tire and a SAW magneto-sensitive sensor is installed on the inner surface of the tire, the magnetic field can be sensed to reduce the wear of the tire. If a SAW force sensor is installed on the inner surface of the tire, the deformation of the tire will stress the amorphous wire. The SAw force sensor can monitor the tire pressure. According to reports, approximately 250,000 accidents in the United States each year are caused by insufficient tire pressure, and a 20% reduction in tire pressure will reduce tire life by 15%.

(2) Car navigation sensors: Japan's Aichi Steel Corporation and Nagoya University jointly developed the use of amorphous wires in the Automated Highway System (AHS). The goal is to use amorphous wire GMI sensors to automate the car's navigation on highways. Among them, magnetic labels made of permanent magnetic materials are fixed on the road surface according to certain rules, and a switch-type GMI sensor made of amorphous wires is mounted on the vehicle. The car uses the sensor to track the magnetic label to realize the automatic navigation function while driving. In such applications, the ability of sensors to resist environmental interference is particularly important. It is said that the dedicated GMI sensors developed by Aichi Steel have solved related problems. The various sensors developed using the unique effects of nano-amorphous wires have great potential for application in the automotive industry, automation control, various security inspections, and defense military industry.

(to be continued)