Development Of A Portable Device With Low Intensity Pulsed Ultrasound And Its Effect On Cartilage

With the continuous improvement of medical level,people put forward new requirements for miniaturization and intellectualization of medical devices and equipment.Bone fracture and cartilage injury have always been a difficult problem for people because of the long course,difficult self-healing,pain,which can seriously affect the life's quality of patients.Clinically,the common treatment methods are drug therapy and surgical intervention,but drug therapy is generally difficult to achieve the desired effect,and surgical intervention of the wound is too large.Ultrasonic treatment has the advantages of noninvasive,convenient and controllable.Currently,foreign countries have approved the fracture healing therapeutic apparatus for clinical use,which is a method of applying Low intensity pulsed ultrasound?LIPUS?for the treatment of fresh fractures and non-union.Studies have reported that 20-minute LIPUS treatment once a day can accelerate the healing of 38%of fresh fractures and 86%of non-union^[1-3].However,the parameter fixation of fracture healing therapeutic device has limited therapeutic effect on repairing cartilage damage and other diseases.Therefore,it is necessary to develop a portable device for cartilage repair.This paper introduces a design method of a portable low-intensity pulsed ultrasound device with adjustable parameters,and studies the influence of LIPUS on the functional state of cartilage by processing primary chondrocytes and metatarsal tissues with different parameters output by self-developed ultrasonic device.MethodsPart I Design a portable device with low-intensity pulsed ultrasound1.The system hardware is mainly composed of low-power single-chip microcomputer,signal excitation module,power amplifier module,no-load protection module and power supply module.MSP430F149,a single-chip microcomputer,is the core of the whole hardware structure,and responsible for output controlling signal,no-load monitoring and alarm,key response and display output.The signal excitation and power amplifier module is responsible for signal generation,voltage amplification,power amplification and resonance matching of the transducer,so as to effectively drive the ultrasonic transducer to output the rated energy.The no-load protection module is responsible for sampling the voltage signal of the output terminal and feeding it back to the single-chip microcomputer.The battery-powered unit provides digital and analog circuits with different isolation working power supplies and voltage conversion through the dc-dc power isolation module.2.Software design of portable low-intensity ultrasonic device.System program was written and debuged in the development environment of IAR-EW for MSP430.The ultrasonic output with different intensity,duty ratio and time can be controlled by the single chip microcomputer through the key input to select parameters,and the output can be automatically cut off and the alarm can be started when the transducer is in no-load,so as to avoid the damage of the transducer due to excessive heating caused by no-load.3.Measurement and evaluation of the device system.The oscilloscope is used to test the electrical signal and evaluate the frequency accuracy and working stability of the device system;The milliwatt level ultrasonic power meter is used to test and evaluate the acoustic power output of the transducer.The response performance and sensitivity of the device system are tested under no-load conditions.Part II Studies on the functional activities of cartilage by LIPUS with three different parameters1.Using self-developed portable device output low intensity pulsed ultrasound with frequency of 1.5 MHz,and adjustable parameters for LIPUS??intensity of 30 mW/cm²,duty ratio of 20%?,LIPUS??intensity of 30 mW/cm²,duty ratio of 40%?,and LIPUS??intensity of 50 mW/cm²,duty ratio of 20%?,experiment diveded for three kinds of LIPUS treatment group and control group.2.Primary chondrocytes of newborn mice were continuously treated with LIPUS as described above for 3 days,and cck-8 was used to test chondrocyte activity 2 hours after treatment each day.3.Primary chondrocytes of newborn mice were continuously treated with LIPUS of the above parameters for 3 days,and the proliferation of chondrocytes tested by EdU instillation method,Col2,Acan,ColX tested by quantitative PCR and the apoptosis of chondrocytes tested by TUNEL,after 2h of treatment on the third day.4.The above parameters of LIPUS were used to continuously treat in vitro cultured bone embryo tissue for 7 days,and the tissue morphology was observed by taking photos on day 0and day 7,and the growth rate of full-length and cartilage at 7 days were measured and calculated.Result1..Hardware design of low-intensity pulse ultrasonic deviceFind out the main chip types of functional modules that meet the research requirements,get familiar with the chip structure and application,carry out hardware design,draw and weld PCB boards,and debug the functions of each module.2.Software design of low-intensity pulse ultrasonic deviceFamiliar with the internal architecture of MSP430 and it's C language instruction set,designed software process according to established technical indicators,wrote programs on the IAR-EW platform,and conducted software and hardware debugging.3.The performance of the test and evaluation device system is stable,and the output parameters meet the technical specificationsThe measurement and evaluation of the operating frequency,output power and no-load protection performance of the device system can meet the research and design requirements.4.LIPUS promotes chondrocyte activity,proliferation,and expression of Col2 and Acan genesOn the first day after LIPUS treatment,there was no significant difference between the groups.Since day 2 of LIPUS treatment,chondrocyte activity has increased in each LIPUS groups compared with the control group.After 3 days of continuous LIPUS treatment,the EdU positive cells rate in each LIPUS group was significantly higher than that in the control group.According to the results of fluorescence quantitative PCR,LIPUS raised mRNA expression level of cartilage matrix related gene Col2 and Acan.The effect of LIPUS?group is most obvious.5.LIPUS can inhibit the expression of ColX gene and apoptosis of chondrocytesChondrocytes treated with LIPUS for 3 days were detected by quantitative fluorescence PCR,and it was found that LIPUS can reduce the expression level of ColX,a gene involved in chondrocyte maturation and differentiation.TUNEL assay showed that the apoptosis rate of chondrocytes in the LIPUS treatment group was lower than that in the control group.The LIPUS?group effect is most obvious.6.LIPUS promote the growth of bone and cartilageUsing the metatarsal cultured in vitro for 7 days to evaluate the effects of bone growth which treatment by LIPUS treatment,LIPUS?,?group can promote bone and cartilage growth,and LIPUS?group compared with the control group has no significant difference.Conclusion1.Design a low intensity pulsed ultrasonic device which is portable and parameter adjustable,with stable output and high safety.2.LIPUS treated chondrocytes continuously for 3 days,promoting their activity,proliferation and expression of Col2 and Acan genes related to cartilage matrix,inhibiting ColX expression and chondrocyte apoptosis.3.LIPUS continuously treated cultured metatarsal bone for 7 days can promote the growth of bone and cartilage.4.The effect of LIPUS is parameter-dependent,and intensity of 30mW/cm² and duty cycle of 40%is the best of the three LIPUS groups.