Pressure sensors have been around for a long time, so they are not unfamiliar to most people. To enhance understanding of pressure sensors, this article will introduce the pressure technology and usage precautions. If you are interested in pressure sensors, please continue reading.
I. Pressure Technology of Pressure Sensors
There are many different pressure sensing technologies on the market today. Some of the most commonly produced technologies by manufacturers around the world are as follows:
1. Capacitive – Capacitive pressure sensors are typically favored for high-volume OEM applications. Detecting changes in capacitance between two surfaces allows these sensors to sense extremely low pressure and vacuum levels. In our typical sensor configuration, a compact housing contains two spatially close, parallel, electrically isolated metal surfaces, one of which is essentially a diaphragm capable of slight bending under pressure. These rigidly fixed surfaces (or plates) are mounted so that bending of the components alters the gap between them (effectively forming a variable capacitor). The resulting change is detected by a sensitive linear comparator circuit with (or ASIC) input, which amplifies and outputs a proportionally high-level signal.
2. CVD Types – Chemical Vapor Deposition (or “CVD”) manufacturing methods bond polycrystalline silicon layers to stainless steel diaphragms at the molecular level, producing sensors with excellent long-term drift performance. Common batch semiconductor manufacturing methods are used to create high-performance polycrystalline silicon strain gauge bridges at a very reasonable cost. CVD structures offer excellent cost-effectiveness and are the most popular sensors for OEM applications.
3. Sputtered Thin Film Types – Sputtered thin film deposition (or “thin film”) creates sensors with the highest combination of linearity, hysteresis, and repeatability. Accuracy can be as high as 0.08% of full scale, while long-term drift is as low as 0.06% of full scale per year.
4. MMS Type – These sensors use micromachined silicon (MMS) diaphragms to detect pressure changes. The silicon diaphragms are isolated from the medium by oil-filled 316SS membranes, and they react in series with the process fluid pressure. MMS sensors utilize common semiconductor manufacturing techniques to achieve high pressure resistance, good linearity, excellent thermal shock resistance, and stability in a compact sensor package.
5. Micro-fusion type - Glass micro-fusion technology, sintering silicon strain gauges onto the back of the cavity with 17-4PH low carbon steel using high-temperature glass powder. The pressure cavity is made of imported 17-4PH stainless steel and is integrally processed, without "O" rings, welds, or leakage risks.
II. Precautions for using pressure sensors
Pressure sensors may encounter many problems when used, and the reasons for this are that several aspects were not considered when selecting the pressure sensor. Since the sensor is one of the most critical variables in your application system, the selection of the pressure sensor is also very important in system engineering design.
Some precautions for using pressure sensors:
1. Determine the pressure to be measured and design the pressure sensor application to monitor changes in pressure for liquid and gas applications.
Do you want to convert pressure to an analog output? The output of the pressure sensor will be one of the most critical issues you'll face. Your choices will differ between analog voltage, current, digital, and wireless outputs. For example, if you choose a low-voltage analog output, you'll have faster response times and a wider temperature range, but you'll find fewer suppliers available for pressure sensors.
2. The cost of the pressure sensor, of course, depends largely on the number of requirements.
Low or high price shouldn't be an immediate deciding factor. Ensure the materials you ask for are used in the process and that each manufacturer provides support. Designing within your budget constraints will be crucial, but make sure you understand what you're getting at a high or low cost. If you've clearly defined your application, this should be a fairly straightforward decision. If you choose the right manufacturers, they will be able to work with you on innovative approaches to make the project work its way. Specifying your application requirements above will help minimize the hassle of selecting the right components you'll face with the number of projects you have. If your application includes certain features, you might want to consider using a buffer or some form of protection for your pressure sensor. Application examples include: process control, car racing, or volume control in any liquid application.
3. Note that when you decide to measure pressure, you need to determine the type of pressure you want to measure, whether it is absolute pressure or differential pressure.
What type of connector do you have for recessed or semi-recessed mounting? Choose one with a similar load capacity, ensuring it exceeds the maximum operating pressure. Additionally, please ensure compliance with specifications regarding power cord, connectors, built-in quick disconnect and output, burst pressure, nonlinearity, hysteresis, creep, bridge resistance, and other environmental conditions. Also consider your ambient temperature, the range of environments the pressure sensor may come into contact with, and corrosive chemicals.
