Manufacturers to monitor fetal monitor device is using the Doppler effect and Doppler effect is named to commemorate the Austrian physicist and mathematician Christian Johann Doppler, he in 1842 first proposed the this theory. The main contents are as follows: the object of radiation wavelength because of the relative motion of wave source and the observer and change. In the movement of the wave front and wave is compressed, the wavelength becomes shorter, the frequency becomes higher (blue shift of the blueshift); when the motion in the source behind, will produce the opposite effect. The wavelength becomes longer and the frequency becomes lower (red shift redshift). Wave speed is high, the effect produced by the greater. According to wave red (blue shift), can be calculated by observing the wave velocity in the direction of movement. Not only mechanical wave has Doppler effect, electromagnetic wave also has Doppler effect.

Using fetal monitor first FHR probe and bandage button, then the coupling agent coated probe surface, placed in the bellies of pregnant women move and find the optimal position of fetal heart and fixed. At this time, the instrument will appear on the waveform and digital display. Note: 1 pregnant women must ensure the lying posture and relax; 2 on the surface of the probe should be evenly coated on the coupling agent to ensure ultrasonic monitoring range, coupling agent is too small will be to narrow the scope of monitoring; 3 bandage elastic should be appropriate, too loose to probe and the skin is not full contact, affecting the accuracy of measurement; too tight will bring pain to pregnant women; 4 when there is a strong movement, contractions or pregnant women when the body moves, the position of the fetal heart may change greatly, then may hear clear fetal heart sound, then you need to adjust ultrasonic probe position, in order to obtain good fetal heart signal. Performance level of clinical care and monitoring products have improved significantly, mainly in monitoring products integrated, modular, specialization, intelligence and information network indicators improved significantly.

Mother fetal monitor is used to monitor the patient's vital signs information and timely response to physiological changes in the patient instantly medical instruments, could help doctors accurately find and solve the problems, and ensure the safety of the patients. This monitoring system has good reliability, accuracy and stability. Its capacitance detection principle is simple and reliable, and it is based on the change of the distance between two parallel plates. The capacitance and charge storage capacity between a pair of parallel plates are determined by the spacing between parallel plates and the plate area.

In addition, the sealing structure of mother fetal monitor reduces the packaging requirements. Particles or chemicals can not enter the sensor, thereby ensuring the reliability of the product. The structure and symmetry of the product are designed to improve the stability, linearity and lateral sensitivity of the product. Generally, the temperature coefficient is less than 0.05FS / ~C, and the lateral sensitivity is less than 3%. This new type of sensor has the following characteristics: compact structure, low power consumption, good reliability, excellent performance.