Pressure Sensors
Pressure sensors use a diaphragm to measure the pressure of a gas or liquid, convert it into an electrical signal, and output the signal. There are two types of pressure sensors: those that output measured data in digital format and those that output measured data in analog format, and each type is used for specific purposes and applications. This section presents the features of MinebeaMitsumi’s pressure sensors and examples of their applications.
- What Is a Pressure Sensor?
- Pressure Sensors Using MEMS
- Application Examples of Pressure Sensors
- MinebeaMitsumi’s Pressure Sensors
What Is a Pressure Sensor?
A pressure sensor is a device that converts pressure into an electrical signal and outputs the signal. It primarily consists of a pressure-sensitive element that converts pressure into an electrical signal and a signal processing unit that processes the electrical signal. Pressure sensors are used in a wide range of devices and are utilized in various industrial and medical equipment, from blood pressure meters to space rockets. There are various types of pressure sensors, including MEMS, resistive, capacitive, piezoelectric, and optical.
Piezoresistors are placed on a thin film (diaphragm) of the MEMS chip to form a bridge circuit.
Air pressure causes the diaphragm to deflect, which generates stress on the piezoresistor. Pressure is measured based on the differential voltage detected on the bridge circuit.
Pressure Sensors Using MEMS
Pressure sensors using MEMS are mainly of the piezoresistive type, which uses a piezoresistive element as the pressure-sensitive element, and the capacitive type, which detects changes in electrostatic capacitance by electrodes.Both types measure pressure by the deflection of a thin film called a diaphragm.
Pressure sensors using MEMS are widely used in mobile devices such as smartphones because of their ease of mass production, compact size, and low power consumption. They are also able to respond quickly to subtle changes in pressure and are therefore used in medical devices that need to accurately measure low levels of pressure.
- A: Sensor control IC
- B: MEMS pressure sensor
This is an example of a pressure sensor using a MEMS chip. The digital type is a single module package containing a sensor and a sensor control IC (AFE) that processes the sensor signals. The analog type does not include a sensor control IC.
Application Examples of Pressure Sensors
Pressure sensors are used in a wide range of fields, from automobiles to medicine.
In automobiles, pressure sensors are used in hydraulic brakes and other brake systems, and in the medical field, these sensors are used in various catheters and blood pressure meters for accurately measuring the pressure inside a patient’s body. They are also used in a wide range of applications, such as water level detection in washing machines and altitude control of drones.
MinebeaMitsumi’s Pressure Sensors
The pressure sensors offered by MinebeaMitsumi are manufactured using MEMS technology and strain gauge technology, and the interface output format is also divided into analog and digital.
Features
MinebeaMitsumi’s pressure sensors cover a measurement range from −50 kPa to 50,000 kPa, and semiconductor-based pressure sensors using MEMS are used in the range from −50 kPa to 50 kPa.
MinebeaMitsumi also offers pressure sensors in two different interface output formats: analog and digital. As part of its lineup, MinebeaMitsumi has also developed a micro-pressure sensor that can measure low levels of pressure. While conventional pressure sensors have a pressure measurement error of ±266 Pa, the micro-pressure sensor has a pressure measurement error of ±40 Pa for enabling more accurate measurements.
Product Descriptions
| MMR901 | MMR902 | MMR906 | MMR920 | MMS901 | |
|---|---|---|---|---|---|
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| Operating pressure range (kPa) | 0 to 40 | 0 to 40 | 0 to 60 | ±1.96 kPa/±3.92 kPa ±6.86 kPa/±9.80 kPa |
−50 to 50 |
| Resolution (Pa) | 3.3 (0.025 mmHg) |
2.7 (0.02 mmHg) |
3.3 (0.025 mmHg) |
0.002 cmH2O | - |
| Pressure accuracy (Pa) | ±266 (±2.0 mmHg) |
±266 (±2.0 mmHg) |
±266 (±2.0 mmHg) |
±1.0% FS | - |
| Offset voltage (mV) | - | - | - | - | −2.5±4.0 (±4.8 kPa) |
| Span voltage (mV) | - | - | - | - | 42.0±5.5 (±6.5 kPa) |
| Package size (mm) | 7.0 × 7.0 × 7.2 | 7.0 × 7.0 × 7.2 | 5.0 × 6.0 × 7.2 | 7.0 × 7.0 × 7.2 | 6.1 × 4.7 × 8.2 |
| Interface (output format) | SPI | SPI/I2C | SPI | SPI/I2C | Analog |
| Current consumption (mA) | 0.69 | 0.69 | 0.64 | 0.8 mA | 0.1 |
| Operating temperature range (°C) | 0 to 60 | 0 to 60 | 0 to 60 | −40 to 85 | −20 to 100 |
Usage Example
In addition to being used for cuff pressure measurement in blood pressure meters and other medical devices, pressure sensors are also used for gas meter leak detection, abnormal pressure detection, and fuel supply pressure detection. Also, pressure sensors using silicon on sapphire (SOS) technology, in which a silicon film is crystallized and grown on a sapphire substrate, have been installed on the H-IIA rocket, and are also used in altitude control of drones.