A wireless power transmission system for implantable devices in freely moving rodents

Reliable wireless power delivery for implantable devices in animals is highly desired for safe and effective experimental use. Batteries require frequent replacement; wired connections are inconvenient and unsafe, and short-distance inductive coupling requires the attachment of an exterior transmitter to the animal’s body. In this article, we propose a solution by which animals with implantable devices can move freely without attachments. Power is transmitted using coils attached to the animal’s cage and is received by a receiver coil implanted in the animal. For a three-dimensionally uniform delivery of power, we designed a columnar dual-transmitter coil configuration. A resonator-based inductive link was adopted for efficient long-range power delivery, and we used a novel biocompatible liquid crystal polymer substrate as the implantable receiver device. Using this wireless power delivery system, we obtain an average power transfer efficiency of 15.2 % (minimum efficiency of 10 % and a standard deviation of 2.6) within a cage of 15 × 20 × 15 cm³.     

可植入人体医疗设备的无线能量传输系统仿真分析

针对传统可植入人体医疗设备供能方式的不足,运用谐振耦合无线能量传输技术,设计可用于心脏起搏器等医疗设备的电能传输系统。结合植入式医疗设备尺寸小的特点,引入8字形线圈结构,采用有限元仿真软件分析各相关参数对于输出功率的影响,得到系统的最优参数。分析了在人体模型中产生的磁感应强度和电场强度分布,参考国际非电离辐射防护委员会（ICNIRP）制定的限值进行对比分析,评估了该系统电磁暴露的安全性,结果表明系统能够安全实现无线能量传输。     

微型植入式医疗电子设备的信号传导机制

微型植入式医疗电子设备是一种长时间埋于人体,用于监测生理特征的微型医疗器械。为了研究微型植入式医疗电子设备如何利用电信号实现植入物与体表检测设备的通信,并分析信号传导机制,本研究利用数学建模的方法,通过设定合理的边界条件和假设,建立微型植入式医疗电子设备体导通信信道模型。为了验证体导通信信道模型的解的准确性,建立了等效的数值解模型,通过分析体导通信信道模型和数值解模型的结果,发现两种模型的误差小于1%。为了验证体导通信信道模型与实验结果的一致性,选用文献中的实验数据来进行验证,通过对比实验结果与体导通信信道模型计算结果,发现体导通信信道模型的解和实验结果误差小于4 dB,具有良好的一致性。因此,体导通信信道模型的解是准确的,体导通信信道模型与实验也有较好的一致性。     

A new hermetic antenna for wireless transmission systems of implantable medical devices

In implantable medical devices (IMDs), the need of telemetry systems able to provide wireless bidirectional communication to interrogate and remotely program the device, as well as to monitor the physiological status of the patient, is growing. The object of the present study was to evaluate a new hermetic antenna for wireless short-range transmission system for IMDs which would assure reliable long-term functioning due to the high level of hermeticity of antenna's housing that limits the influence of body tissue environment on transmitted signals. Experimental tests were conducted on three different prototypes to evaluate the most efficient antenna configuration for transmission both in the air and through a mixture simulating the human thorax. Further tests were performed to assess the influence of electro-catheters connected to IMDs on transmitted signals. Results showed that the hermetic antenna guarantees a good wireless transmission both in the air and through the human thorax simulator. The results also show that the presence of an electro-catheter can influence the effective radiated power (ERP) transmitted depending on its position in relation to the telemetric circuitry. Both a controlled increase of the ERP without exceeding the limits imposed by rules and the optimization of the tuning between the antenna and the transmitter can assure a reliable short-range transmission (several meters) using the new hermetic antenna proposed.     

基于无线能量传输技术的植入式三路心电遥测系统

目的 为全方位监测心电信号并弥补单一导联心电检测的不足,设计并实现了一种基于无线能量传输技术的植入式三路心电遥测系统.方法 系统由无线能量传输设备供能,植入式微型电子胶囊检测心电信号,数据记录仪无线接收数据并由数据处理软件处理.直流供电下分别采用模拟心电信号、正弦信号、方波信号通过模拟实验验证了系统的性能.无线供能下信号线屏蔽后并埋在猪肉中进行体外实验.结果 模拟实验胶囊能够采集三种信号,体外实验测得有噪声的信号波形.结论 直流供电下胶囊正常工作,无线供能下猪肉对磁场有一定程度的屏蔽作用.     

One implantable three-lead ECG radio telemetry system based on wireless power transmission technology

目的 为全方位监测心电信号并弥补单一导联心电检测的不足,设计并实现了一种基于无线能量传输技术的植入式三路心电遥测系统.方法 系统由无线能量传输设备供能,植入式微型电子胶囊检测心电信号,数据记录仪无线接收数据并由数据处理软件处理.直流供电下分别采用模拟心电信号、正弦信号、方波信号通过模拟实验验证了系统的性能.无线供能下信号线屏蔽后并埋在猪肉中进行体外实验.结果 模拟实验胶囊能够采集三种信号,体外实验测得有噪声的信号波形.结论 直流供电下胶囊正常工作,无线供能下猪肉对磁场有一定程度的屏蔽作用.     

Improvement in magnetic field immunity of externally-coupled transcutaneous energy transmission system for a totally implantable artificial heart

Transcutaneous energy transmission (TET) that uses electromagnetic induction between the external and internal coils of a transformer is the most promising method to supply driving energy to a totally implantable artificial heart without invasion. Induction-heating (IH) cookers generate magnetic flux, and if a cooker is operated near a transcutaneous transformer, the magnetic flux generated will link with the external and internal coils of the transcutaneous transformer. This will affect the performance of the TET and the artificial heart system. Hence, it is necessary to improve the magnetic field immunity of the TET system. During operation of the system, if the transcutaneous transformer is in close proximity to an IH cooker, the electric power generated by the cooker and coupled to the transformer can drive the artificial heart system. To prevent this coupling, the external coil was shielded with a conductive shield that had a slit in it. This reduces the coupling between the transformer and the magnetic field generated by the induction cooker. However, the temperature of the shield increased due to heating by eddy currents. The temperature of the shield can be reduced by separating the IH cooker and the shield.     

Fundamental study of an electric power transmission system for implanted medical devices using magnetic and ultrasonic energy

 In this paper, the authors propose a novel electric power supply system for implanted medical devices. The system is noninvasive and uses two kinds of energy, magnetic and ultrasonic. The system can provide high power levels harmlessly. The energies are obtained by two types of vibrator, i.e., piezo and magnetostriction devices. A prototype was built and it was verified experimentally that the system is basically able to provide power. At high frequencies, such as 100 kHz, the output power was higher than the conventional system using a transformer. The normalized output power per unit volume also exceeded the transformer system. Received: October 3, 2002 / Accepted: February 3, 2003     

无线供能系统接收装置的结构设计

目的 无线供能系统的接收装置囿于尺寸限制难以满足越来越高的能量要求,提高空间利用率是解决这一难题的关键.方法 从接收装置的姿态稳定性和体内温升安全性角度出发,通过实验方法确定接收装置磁芯的较优形状,并在给定尺寸约束下根据几何关系建立方程解出磁芯尺寸与导线股数和匝数,从而实现接收装置的结构优化.应用该方法对肠道机器人无线供能模块的能量接收装置进行了设计和实验.结果 在外形≤φ10 mm×10 mm的约束下,接收装置输出功率可以保证在500 mW以上,并且符合温升安全性要求.结论 实验结果表明了这种带约束的对称性设计方法的有效性.     

Improvement of cardiac pumping efficiency by adenosine

Pflügers Archiv - European Journal of Physiology -     

Evaluation of SAR in a human body model due to wireless power transmission in the 10 MHz band

This study discusses a computational method for calculating the specific absorption rate (SAR) due to a wireless power transmission system in the 10 MHz frequency band. A two-step quasi-static method comprised of the method of moments and the scalar potential finite-difference method are proposed. The applicability of the quasi-static approximation for localized exposure in this frequency band is discussed by comparing the SAR in a lossy dielectric cylinder computed with a full-wave electromagnetic analysis and the quasi-static approximation. From the computational results, the input impedance of the resonant coils was affected by the existence of the cylinder. On the other hand, the magnetic field distribution in free space and considering the cylinder and an impedance matching circuit were in good agreement; the maximum difference in the amplitude of the magnetic field was 4.8%. For a cylinder-coil distance of 10 mm, the difference between the peak 10 g averaged SAR in the cylinder computed with the full-wave electromagnetic method and our quasi-static method was 7.8%. These results suggest that the quasi-static approach is applicable for conducting the dosimetry of wireless power transmission in the 10 MHz band. With our two-step quasi-static method, the SAR in the anatomically based model was computed for different exposure scenarios. From those computations, the allowable input power satisfying the limit of a peak 10 g averaged SAR of 2.0 W kg(-1) was 830 W in the worst case exposure scenario with a coil positioned at a distance of 30 mm from the chest.     

The changes in the transmission functioning of the ulnar nerve in a high power magnetic field

INTRODUCTION: The present study aims at exploring the changes in the functioning of the ulnar nerve in a high power magnetic field. METHODS: 12 volunteers with a healthy peripheral nervous system participated in the study. The ulnar nerve was selected from the upper organs as the site for study. The functioning of both the sensory and motor parts of the ulnar nerve in normal conditions was electromyographically tested. Then, using the same setting, the functioning of the nerve was electromyographically tested within a high power magnetic field (0.2 Tesla). With regard to the sensory function, the distal latency and the amplitude were examined. With regard to the motor section, the duration, amplitude of the evoked potentials, and latency from two sites--distal and proximal--were examined. These results of the two readings, taken in normal condition and in a high power magnetic field, as well as the motor neural conduction velocity, were compared. RESULTS: The statistical analyses indicated that the changes in both the distal latency and amplitude of the sensory part of the ulnar nerve were significant. However, the changes in the motor function of the nerve were not significant.     

Production of extra-cellular slime by Staphylococcus epidermidis during stationary phase of growth: its association with adherence to implantable devices.

A method of optimising slime production produced by Staphylococcus epidermis and its quantitative assay was developed, which gave a preliminary indication of its identity and an assessment of the correlation between slime production and adherence of the organism to implants. After inducing vigorous growth in brain heart infusion broth to stationary phase, all nutrients were removed by washing and the organisms resuspended in sterile deionised water with added magnesium. After further incubation the culture was centrifuged and the supernatant reacted with alcian blue in 50 mM magnesium chloride/sodium acetate solution, and the amount of bound dye was measured spectrophotometrically at 620 nm after its resolubilisation using sodium dodecyl sulphate. Large quantities of slime were produced by some, but not all, strains. Preliminary electrophoresis of the slime showed mobility and staining similar to that of the glycosaminoglycans. Adherence was tested by growing strains in wells of tissue culture plates and aspirating the supernatant after incubation. After fixation and staining of adherent growth the amount of bound stain was determined spectrophotometrically after its elution with ethanol. In this series of organisms there was no correlation between the result of tests for adherence or production of extracellular slime, and no correlation between either of these and the clinical source of the organisms.     

乙肝免疫球蛋白免疫阻断HBV母婴垂直传播机制的研究

目的 探讨乙肝免疫球蛋白免疫阻断HBV母婴垂立传播。方法 对孕妇HBsAg( )者进一步检测HBV M及HBV DNA，根据病情分别采用乙肝疫苗和HBIG免疫阻断，并对新生儿脐血进行HBVM及HBV DNA检测以了解新生儿感染情况。结果 采用HBIG阻断HBV新生儿无l例发生感染。结论 孕早期检测HBV M，早期诊断、早期干预和早治疗，是阻止患儿出生的关键。     

Calculation of induced current densities for humans by magnetic fields from electronic article surveillance devices.

This paper illustrates the use of the impedance method to calculate the electric fields and current densities induced in millimetre resolution anatomic models of the human body, namely an adult and 10- and 5-year-old children, for exposure to nonuniform magnetic fields typical of two assumed but representative electronic article surveillance (EAS) devices at 1 and 30 kHz, respectively. The devices assumed for the calculations are a solenoid type magnetic deactivator used at store checkouts and a pass-by panel-type EAS system consisting of two overlapping rectangular current-carrying coils used at entry and exit from a store. The impedance method code is modified to obtain induced current densities averaged over a cross section of 1 cm2 perpendicular to the direction of induced currents. This is done to compare the peak current densities with the limits or the basic restrictions given in the ICNIRP safety guidelines. Because of the stronger magnetic fields at lower heights for both the assumed devices, the peak 1 cm2 area-averaged current densities for the CNS tissues such as the brain and the spinal cord are increasingly larger for smaller models and are the highest for the model of the 5-year-old child. For both the EAS devices, the maximum 1 cm2 area-averaged current densities for the brain of the model of the adult are lower than the ICNIRP safety guideline, but may approach or exceed the ICNIRP basic restrictions for models of 10- and 5-year-old children if sufficiently strong magnetic fields are used.     

Intraspecies variability in transmission efficiency of stylet-borne viruses by the pea aphid (Acyrthosiphon pisum)

The efficiency of bean yellow mosaic virus (BYMV; Potyvirus group) tranasmission from pea to pea plants by 36 clones of the pea aphid (Acyrthosiphon pisum) was studied. The efficiency of the clones varied; it was not related to the aphid colour form (green, red or yellow) or the origin of the clone (host plant, geographic area). With alfalfa mosaic virus, the virus-vector relationships concerning transmission efficiency were, in general, similar to those found with BYMV. The behaviour of the clones to the circulative pea enation mosaic virus was, however, different.     

Failure of antibiotic therapy in Staphylococcus epidermidis infection of implantable venous access devices in patients with AIDS,as documented by molecular typing

ObjectiveTo study the efficacy and safety of high-concentration antibiotic locks in association with systemic antibiotherapy in Staphylococcus epidermidis infections of totally implantable venous access devices (TIVADs) in patients with AIDS.MethodsThirty-one episodes of S. epidermidis TIVAD infection were observed in nine patients. Locks consisted of high concentrations of aminoglycosides or vancomycin according to antibiogram results (susceptibility results obtained with the disk diffusion technique). Genotyping of bacterial strains was performed by pulsed-field gel electrophoresis (PFGE) in 26 of the 31 infectious episodes.ResultsThe infections occurred within a median period of 62 catheter-days. The median duration of systemic antibiotic therapy was 17.5 days in association with a median of three antibiotic locks. Failure as defined by the occurrence of a novel episode within 2 months was observed in 17 of the 31 infections (58%). According to the PFGE results, relapse with the same strain of S. epidermidis or reinfection with a different strain of S. epidermidis could be assigned to 10 episodes which failed to respond to therapy. Relapse was observed in six of 10 episodes. Four episodes were followed by the occurrence of a novel infection with a different S. epidermidis strain. In one patient, a relapse occurred despite TIVAD removal.Conclusion: Our observations further document the poor efficacy of associating antibiotic locks with systemic antibiotic therapy for the treatment of TIVAD infections in patients with AIDS.     

A biotin-avidin technique for the localisation of membrane-bound monoclonal antibodies by low power transmission electron microscopy

A biotin-avidin horseradish peroxidase system is described for the localisation of membrane-bound monoclonal antibodies by low power transmission electron microscopy. An indirect bridge technique was used, with a biotin-labelled goat anti-mouse immunoglobulin antibody and horseradish peroxidase-conjugated avidin D. The technique provided preparations of high morphological and ultrastructural quality which facilitated accurate cellular identification. Positive immunostaining was specific and precisely defined.