| The incidence and mortality of cancer are increasing all over the world.China is one of the countries with high cancer cases,where cancer-related death ranks the first among the death causes of residents.Major treatments for cancer include surgical resection,chemotherapy,radiotherapy,immunotherapy,targeted therapy,etc.Although these treatments can prolong the survival of patients to a certain extent,they may cause different degrees of toxic and side effects,and even great pain to patients.During the era of electricity,abundant studies have been conducted to investigate the effects of electromagnetic field on human health.In particular,the application of electromagnetic fields in disease treatment has become a research hotspot.Some studies have found that electromagnetic fields not only have significant effects in the treatment of cancer,diabetes,neural system diseases and immune system diseases,but also can accelerate the healing of skin wounds,promote the recovery of musculoskeletal injury,and improve the body’s antioxidant capacity.Compared with traditional therapy,electromagnetic therapy has the advantages of higher safety,less pain,and no side effects.Although many studies have proved that electromagnetic fields play a positive role in the treatment of diseases,its theory and technology are not mature yet.At present,the proposed biological mechanism of electromagnetic fields includes induced electric field and current mechanism,forced ion mechanism,free radical pair mechanism,etc.But no consensus has been reached.Therefore,the main problems faced by electromagnetic therapy are two-folds: unclear biological mechanism of electromagnetic field and the lack of electromagnetic therapy equipments.This thesis aims to develop a wearable bio-inspired electromagnetic field emitter for cancer treatment based on the previous work of our research group.Wearable medical devices can be worn or carried by patients,so the treatment is not limited by location or time,which can greatly improve the quality of life of patients.Electromagnetic field emitter is a key component of wearable electromagnetic therapy device,which determines the electromagnetic field intensity and uniformity at the treatment site.At present,electromagnetic field emitting coils used in electromagnetic therapy research include Solenoid coil,Helmholtz coil and Braunbeck coil,but these coils have large volume and uneven distribution of external electromagnetic field,so they are not suitable for wearable electromagnetic therapy device.First,this work has designed a double-coil system to emit electromagnetic field.Through simulation comparison,it has been found that the double-coil system with the enameled wire diameters of 0.6 mm for the inner coil and 0.5 mm for the outer coil shows the best performance.Then,the outer radius and the number of turns for both the inner coil and outer coil have been optimized for the double-coil system with an inner radius of 5 mm.It has been found that the double-coil with an outer radius of 8 mm and25 turns for the inner coil and an outer radius of 11.5 mm and 42 turns for the outer coil possesses the best performance,which can meet the design requirements of this work.Then,the hexagonal structure of honeycomb has been adopted as the bionic prototype to design the coil array.By comparing the simlulated eletromagnetic fields of the arrays with different coil spacing,it has been found that the array with coil spacing of 26 mm is not only stronger but also more uniform than the others.In order to verify the simulation results,this thesis has designed a wire winding rod for the production of electromagnetic field emitter,built an electromagnetic field emission system,and measured the electromagnetic field intensity generated by a single emitter and emitter array.The comparison with the simulation results shows that the trend of the actual measurement results is consistent with that of the simulation results,and the difference is within the acceptable range.Subsequently,colony formation assay with Hela cell has been conducted to verify the inhibitory effect of bio-inspired electromagnetic field（0.5 Hz 35 μT-70 μT）emitted by the emitters on the proliferation of cancer cells.100（low density）and 1000（high density）Hela cells have been seeded in a culture plate with a diameter of 3.5 cm.After 6-day irradiation of bio-inspired electromagnetic field,no colonies can be identified in the low-density experiment group and only a few cell colonies can be seen in the high-density experiment group.The experimental results prove the feasibility and effectiveness of the emitter design.Finally,this thesis has optimized bio-inspired electromagnetic field parameters based on the inhibition of Hela cell proliferation.According to the literature,pulsed square wave electromagnetic field with a fundamental frequency of Schumann resonance（7.83 Hz）has been chosen and the electromagnetic field intensity been set to600 μT and 200 μT.It has been found that the morphology of Hela cells begins to change after a 2-day exposure to 7.83 Hz 600 μT electromagnetic field,and apoptosis can be observed after 4-day irradiation.The morphological change of Hela cells has also been observed after the irradiation with 7.83 Hz 200 μT electromagnetic field.When 5000 Hela cells were seeded in a 3.5-cm culture plate and irradiated by 7.83 Hz600 μT electromagnetic field for 6 days,no colony has been formed in the experiment group.When the number of cells seeded reached 20000,both 600 μT and 200 μT electromagnetic fields can still inhibite the proliferation of Hela cells,whereas 600 μT electromagnetic field shows stronger inhibition.Meanwhile,this thesis has verified that the electromagnetic fields with these two settings have no significant inhibitory effect on the growth of normal cells,such as NIH/3T3 cells.This work has demonstrated a closed-loop scheme of design-simulationoptimization-production-verification: from coil design and simulation optimization,to coil array design and simulation optimization,to electromagnetic field emitter production and actual measurement of electromagnetic field intensity,and finally to cell experiment verification.The work has also systematically proved the feasibility of the design and the inhibitory effect of bio-inspired electromagnetic field on the proliferation of cancer cells.The electromagnetic field emitter developed herein has the potential to be applied in wearable bio-inspired electromagnetic field therapy devices. |
