Case - High Frequency Dynamic Pressure Sensor

In fields such as military engineering, explosive testing, oil and gas exploration, materials and geotechnical mechanics, trauma medicine, and hydraulic power testing, the precise measurement of high-frequency transient pressure waveforms places stringent demands on the dynamic performance of sensors. The SI-90 high-frequency dynamic pressure transmitter is designed specifically for these applications. Through micromachining technology, it achieves miniaturization of the silicon chip, which possesses ultra-high natural frequency, extremely short rise time, and wide frequency response characteristics. It exhibits excellent elastomechanical properties. And its overall performance surpasses that of piezoelectric dynamic pressure sensors, which makes it a reliable choice for high-precision dynamic pressure measurement.

Cade Sharing

A customer from a Chinese university learned about our high-frequency pressure sensors through our website and contacted us to purchase them. The final specifications are as follows:

High-Frequency Dynamic Pressure Sensor
SI-90
Pressure Range: 0-1000 kPa
Bandwidth: 0-200 kHz
Output: 0-5 V
Connection Method: G 1/4 threaded mounting
Direct cable output

Product Features

All stainless steel housing, excellent corrosion resistance
Wide pressure measurement range
High natural frequency up to 2MHz
Stable operation and strong anti-interference ability
Original imported components, reliable performance, small size, light weight, complete range of types, high cost-effectiveness
Wide range of measurable media

Differences Between High-Frequency Dynamic Pressure Sensors And Ordinary Pressure Sensors

1. High-frequency dynamic pressure sensors have a high natural frequency, ranging from 150KHz to 2MHz. Ordinary pressure sensors typically have a natural frequency less than 10KHz.

2. High-frequency dynamic pressure sensors have a bandwidth of up to 200KHz. Ordinary pressure sensors have a bandwidth of 0-100Hz or lower.

3. High-frequency dynamic pressure sensors have a rise time in the microsecond range, while ordinary pressure sensors have a rise time in the millisecond range.

4. High-frequency dynamic pressure sensors can only measure dynamic pressure, while ordinary pressure sensors can measure static pressure and slowly changing pressure.

Measurement Principle

Our high-frequency dynamic pressure sensor, like most ordinary pressure sensors, uses single-crystal silicon as the sensitive diaphragm, utilizing its piezoresistive effect. Pressure causes microscopic deformation of the material, resulting in a significant change in resistivity. A Wheatstone bridge circuit converts this resistance change into a voltage output.

But why can our high-frequency dynamic pressure sensor achieve high-frequency dynamic measurement? There are three reasons:

1. MEMS technology integrates strain resistors, amplification, and compensation circuits onto the same silicon chip. The sensing element is extremely small (micron-sized), lightweight, and has low inertia, allowing it to quickly follow pressure fluctuations and reduce mechanical hysteresis. Therefore, it possesses good high-frequency response capabilities.

2. The flush diaphragm design exposes the sensing element directly to the pressure field, which eliminates the fluid inertia and damping caused by traditional connecting tubes or cavities.

3. A dedicated high-frequency response signal processing circuit converts the signal from the measuring element into a standard current or voltage output signal.

What Does “High Frequency” Specifically Refer To?

The essence of “high frequency” is that the sensor’s mechanical structure has a high natural frequency, thus supporting a wide usable bandwidth, which ultimately achieves a fast response to rapidly changing pressure signals.

1. Natural Frequency

The natural frequency of a sensor which depends on the physical characteristics of the material and structure of the sensor’s sensing element. It is determined during the sensor chip manufacturing process and cannot be changed by subsequent processing. Therefore, the natural frequency is generally only a physical indicator of the dynamic pressure sensor parameters. The natural frequency determines the upper limit of the sensor’s frequency response and reflects the limit of its mechanical system’s response speed.

2. Bandwidth

Bandwidth refers to the frequency range of pressure signals that the sensor can accurately measure. Engineering requirements dictate that the bandwidth must be less than one-fifth of the natural frequency; therefore, the natural frequency determines the upper limit of the bandwidth. However, the actual bandwidth is the result of design trade-offs, set according to parameters such as accuracy and stability, and is far below the limit. Therefore, when selecting a sensor, one should not only look at the natural frequency, but must also clarify the bandwidth specifications, as this represents the true usable frequency.

Application Scenarios

1. Pressure detection of gas explosions.

Generally used in pipeline gas explosion experiments, the pressure range is typically 0.5 MPa to 10 MPa, varying depending on the amount of gas mixed in the experiment, the explosion space, and the installation location.

2. Underwater explosion experiments.

The sensor is generally installed on the inner wall of the underwater instrument, which exposes the pressure-sensitive element of the sensor to the test environment to monitor changes in water pressure before and after the explosion. Pressure data is collected by using a high-frequency data acquisition instrument, which is reconstructed into a pressure waveform, accurately reproducing the instantaneous pressure changes in the surrounding environment during the explosion.

Similar to pressure detection in such explosion conditions, a high-frequency pressure sensor with a response bandwidth of 0-200 kHz is generally selected. The sensor’s rise time is in microseconds, and the entire experiment is relatively short.

3. Pressure measurement under frequently fluctuating conditions.

For example, pressure measurement in reciprocating pumps or hydraulic presses with frequent pressurization and depressurization cycles. Generally, gas pressure changes more rapidly than liquid pressure. Depending on the actual working conditions, a high-frequency pressure sensor with a suitable bandwidth can be selected.