ABSTRACT
Objective To develop a sinusoidal alternating magnetic field therapy system in order to overcome the disadvantages of the single output frequency and the low effective value of the output magnetic field strength of the alternating magnetic field therapy system in the market,of which the frequency and magnetic density both were continuously adjustable. Methods Multi winding Helmholtz coil was used as the magnetic field generator.On the basis of inverter technology,bipolar equivalent area method considering dead zone and variable speed integral incremental PID control algorithm were used to achieve the accuracy control of magnetic frequency and density in the coil.The accuracy of the resulting waveform and the accuracy of the magnetic field strength was verified by simulation calculation and system current and magnetic field strength test.Results The magnetic field treatment system gained high performance,total harmonic distortion (THD)of sine wave met the requirements of international standards.The obtained magnetic density was as expected of the simulation and calculation. Conclusion The device provides continuously adjustable magnetic field,which has a positive effect on the research for the medical staff, and technical references are provided to the research of magnetic field therapy system.
ABSTRACT
According to the principle of immunomagnetic separation, a novel high-efficient immunomagnetic isolator termed as CMSI 100 for the purification of human CD34 + hematopoietic cells was designed and successfully developed. To do this , neodymium iron boron having magnetic properties superior to any other permanent magnet materials was selected as the key parts of CMSI 100 isolator. The core of the magnet assembly was constructed by sandwiching mild steel bars between 4 pieces of magnet bars of neodymium iron boron. Each piece of magnet bars must be limited to the specifications of 3.5cm?2.0cm?0.3cm so that 2 700 gauss magnetic attractive force could be exerted at the magnet surface. Otherwise magnetic field above the surface of the magnet assembly is either very stronger or weaker, both of which are not beneficial to the enrichment of CD34 + hematopoietic cells. With CMSI 100 immunomagnetic isolator, more than 90% purity and over 95% viability of CD34 + hematopoietic cells could be obtained. These data indicate that CMSI 100 immunomagnetic isolator is as good as the internationally used Isolex TM 50 made by Baxter Company in USA.