China Education Equipment Purchasing News: Hokuriku University of Science and Technology, Japan announced that researchers at the school have developed gold and silver nanoparticles, which can be used to make high-sensitivity biosensors to help doctors check patients ’blood, urine or genes Diagnosis, etc.
The researchers first made gold nanoparticles with a diameter of about 14 nanometers (1 nanometer equals one billionth of a meter), and then covered the surface with a silver film with a thickness of about 4 nanometers, and then covered the silver film with a thickness of 0.1 Nanometer gold forms a structure of gold and silver. Researchers observed the characteristics of this structure and found that it not only has the same sensitivity as pure silver nanoparticles, but also has the characteristics of gold-high chemical stability, and it is easy to combine with related molecules in the organism.
The former professor of the school, who led the research, said: "If you use this nanoparticle, the performance of the biosensor will be dramatically improved, and the cost will be greatly reduced."
Guide to foreign journals:
A sensor is a physical device or biological organ that can detect and feel external signals, physical conditions (such as light, heat, humidity) or chemical composition (such as smoke), and transmit the detected information to other devices or organs.
Sensor classification:
Sensors can be classified with different perspectives: their conversion principles (the basic physical or chemical effects of sensor operation); their use; their output signal types and the materials and processes that make them.
According to the working principle of the sensor, it can be divided into two categories: physical sensors and chemical sensors:
Classification of sensor working principles Physical sensors apply physical effects, such as piezoelectric effect, magnetostriction, ionization, polarization, thermoelectric, photoelectric, magnetoelectric and other effects. The small changes of the measured signal will be converted into electrical signals.
Chemical sensors include those that use chemical adsorption, electrochemical reactions, and other phenomena as the causal relationship. The small changes in the measured signal quantity will also be converted into electrical signals.
Some sensors can neither be classified as physical nor chemical. Most sensors operate on the basis of physical principles. There are many technical problems with chemical sensors, such as reliability problems, the possibility of large-scale production, and price problems. After solving such problems, the application of chemical sensors will have a huge growth.
The application fields and working principles of common sensors are listed in the table below.
1. Sensors are classified according to their use
Pressure-sensitive and force-sensitive position sensors
Liquid level sensor energy consumption sensor
Speed ​​sensor acceleration sensor
Radiation sensor thermal sensor
24GHz radar sensor
2. Sensors are classified according to their principles
Vibration sensor humidity sensor
Magnetic sensor gas sensor
Vacuum sensor biosensor, etc.
3. The sensor is classified according to its output signal as a standard
Analog sensor-converts the measured non-electrical quantity into an analog electrical signal.
Digital sensor-convert the measured non-electrical quantity into digital output signal (including direct and indirect conversion).
Digital sensor-converts the measured signal into a frequency signal or short-period signal output (including direct or indirect conversion).
Switching sensor-when a measured signal reaches a certain threshold, the sensor outputs a set low or high level signal accordingly.
4. Sensors are classified according to their materials
Under the influence of external factors, all materials will make corresponding and characteristic reactions. Among them, the most sensitive materials to external effects, that is, those with functional characteristics, are used to make the sensitive components of the sensor. From the viewpoint of applied materials, the sensors can be divided into the following categories:
(1) According to the type of materials used
Metal polymer ceramic mixture
(2) According to the physical properties of the material: conductor insulator semiconductor magnetic material
(3) According to the crystal structure of the material:
Single crystal polycrystalline amorphous material
Sensor development work closely related to the use of new materials can be summarized in the following three directions:
(1) Explore new phenomena, effects and reactions in known materials, and then make them available for practical use in sensor technology.
(2) Explore new materials and apply known phenomena, effects and reactions to improve sensor technology.
(3) Explore new phenomena, new effects and reactions on the basis of researching new materials, and implement them in sensor technology.
The progress of modern sensor manufacturing depends on the development of new materials and sensitive components for sensor technology. The basic trend of sensor development is closely related to the application of semiconductors and dielectric materials. Table 1.2 shows some materials that can be used in sensor technology to convert energy forms.
5. Sensors are classified according to their manufacturing process
Integrated sensor thin film sensor thick film sensor ceramic sensor
Integrated sensors are manufactured using standard process technology for producing silicon-based semiconductor integrated circuits. Usually also part of the circuit used to initially process the signal under test is integrated on the same chip.
The thin film sensor is formed by depositing a thin film of a sensitive material on a dielectric substrate (substrate). When using a hybrid process, part of the circuit can also be fabricated on this substrate.
The thick film sensor is made by coating the slurry of the corresponding material on the ceramic substrate. The substrate is usually made of Al2O3, and then heat treated to form the thick film.
The ceramic sensor is produced using a standard ceramic process or one of its variant processes (sol-gel, etc.).
After proper preparatory operations are completed, the formed element is sintered at high temperature. Thick film and ceramic sensors have many common characteristics. In some aspects, thick film technology can be considered as a variation of ceramic technology.
Each process technology has its own advantages and disadvantages. Due to the low capital investment required for research, development and production, and the high stability of the sensor parameters, it is more reasonable to use ceramic and thick film sensors.
(Courtesy of HVAC experts)
6. Sensors are classified according to the purpose of measurement
The physical sensor is made by using the characteristic that some physical properties of the measured substance change obviously.
Chemical sensors are made using sensitive elements that can convert chemical quantities such as the composition and concentration of chemical substances into electrical quantities.
Biological sensors are sensors that use the characteristics of various organisms or biological substances to detect and identify chemical components in living organisms.
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