Ultrasonic diagnostic instrument which generates incident ultrasonic wave (transmitted wave) and receives reflected wave (recovered) through the probe，ultrasound probe is an important part of ultrasonic diagnostic instrument.
Current probe can transmit and receive ultrasonic, acoustic signal conversion, can transform by electrical signals from the host for the high frequency oscillation of ultrasonic signals, and can be reflected from the organization organs of ultrasonic signal into electrical signal and display in host monitor, ultrasound probe is made use of this principle. As the main task of the hardware is the probe internal component of the chip, in the state of electricity, it can produce elastic deformation, thus producing ultrasonic. On the contrary, when the ultrasonic wave through the chip, and can cause it to produce elastic deformation, and then cause the voltage change, and finally through the signal processing board to the corresponding electrical signal changes to complete the detection of the object image exploration, this processing process is called piezoelectric effect.
What is piezoelectric effect:
Piezoelectric effect generally refers to a kind of acoustoelectric reversible effect of crystals in elastic media. Crystals with piezoelectric effect are called piezoelectric crystals. At present, the commonly used crystal materials are artificial or natural crystals such as lithium sulfate, quartz, barium titanate, lead zirconate and so on. Barium titanate and lead zirconate are polycrystalline ceramics sintered at high temperature. After the blank is burned into ceramic body, the required geometric dimensions are obtained through appropriate grinding and trimming. After polarization with high-voltage DC electric field, they have piezoelectric properties and become energy conversion devices.
Piezoelectric effect can be divided into positive piezoelectric effect and inverse piezoelectric effect.
Positive piezoelectric effect:In a certain direction of the crystal or ceramic body, mechanical pressure is applied to deform it, and the two stress surfaces of the crystal or ceramic produce charges with opposite symbols; The deformation direction is opposite, the charge polarity on both sides also changes, and the charge density is directly proportional to the applied mechanical force. This kind of charge effect on the surface caused by mechanical force is called positive piezoelectric effect.
Inverse piezoelectric effect:When voltage is applied along the axial direction on the crystal and ceramic surface, the geometric strain is caused under the action of electric field. The voltage direction changes, and the mechanical strain direction also changes. The deformation is proportional to the electric field. This deformation effect caused by electric field is called inverse piezoelectric effect. Due to different cutting directions and geometric dimensions, the natural frequencies of mechanical vibration are also different. When the frequency of the applied alternating voltage is consistent with the natural frequency, the mechanical vibration is the strongest. When the frequency of the applied alternating voltage is consistent with the natural frequency, the charge is also the most. In the ultrasonic wave diagnostic instrument, the frequency of the excitation pulse must be the same as the natural frequency of the probe
What are the precautions in the use of ultrasound probe?
1. Power off and plug.
The B-ultrasound probe belongs to the B-ultrasound diagnosis system first, so it must be connected to the diagnosis system to work normally. At this time, it should be noted that before connecting the probe, it is carried out under power off; Before plugging the probe from the host, the host power must also be cut off.
If the operation is carried out under the condition of power on, the plug-in of the probe will age rapidly due to repeated contact conduction and disconnection, and even burn the wire or chip in the probe due to strong current generated by multiple instantaneous conduction of current.
2. No impact.
B-ultrasound probe is an important core component of B-ultrasound machine. It is strictly prohibited to knock, drop and collide during use.
3. Keep the environment dry and clean.
When the probe is not in use, it shall be put into the probe protection box of the machine, and the protection box shall be kept dry and clean.
4. Try qualified coupling agent.
Qualified ultrasonic coupling agent shall be used, and oil or other chemical solvent components are strictly prohibited.
5. Wipe and clean with soft objects.
The probe must be cleaned after use. The surface of the probe can be soaked in water with a soft cloth and cannot be scrubbed with hard paper, otherwise it is easy to damage the acoustic lens of the probe.
6. Avoid vibration damage of external instruments.
If B-ultrasound is used for external positioning of lithotriptor, therapeutic machine and other high-power ultrasonic equipment or vibration equipment, the probe shall be removed before the positioning is completed and the high-power equipment or vibration equipment is not started, so as to ensure that the high-power ultrasound or vibration does not act on the B-ultrasound probe, otherwise the probe and are easy to be damaged.
7. Do not immerse in liquid.
The probe structure is non watertight. Once liquid is immersed in the probe, it may cause short circuit of internal wires or burn out of some PCB boards, resulting in the failure of the diagnostic system. Therefore, when we use the ultrasonic probe, no liquid is allowed to submerge the suture under the probe.
8. Avoid using in places with strong electromagnetic interference.
Some signal processing boards are integrated in the probe assembly. When used in the environment of strong electromagnetic interference, it is easy to cause display image interference. Therefore, when using, try to avoid using in places with strong electromagnetic interference.