Development, fabrication, and applications of biomedical electrodes

生物医用电极作为一种能够有效地将生物体电化学活动产生的离子电位转换成测量系统电子电位的传感器,广泛应用于现代临床检测和生物医学测量.近年来,由于生物医用电极在心电图ECg、脑电图EEg、肌电图EMg以及电阻抗成像EIT等领域的迫切应用需求,新型生物医用电极结构及其高效低成本的制造方法不断涌现,生物医用电极制造技术获得飞速发展.本文通过对现有的生物医用体表电极进行了分类(包括传统银/氯化银电极、微针电极、纺织柔性电极、柔性衬底电极、泡沫结构电极、绝缘干电极),分别对其制造工艺过程与使用方法进行了综述,并对其已有或潜在的应用领域进行详细分析,最后对生物医用电极的应用前景进行了展望.Biomedical electrodes convert the ion potential generated by electrochemical activities into an electronic potential that can be measured by instrumentation systems; they are widely used as sensors in modern clinical detection and biomedical measurement.In recent years, with increasing applications in the fields of electrocardiography(ECG), electroencephalography(EEG), electromyography(EMG), and electrical impedance tomography(EIT), a great number of new biomedical electrodes with novel structural design and new material selection have been explored and developed; low-cost fabrication methods are also being intensively studied.In this paper, biomedical electrodes are classified into five types, including traditional silver/silver chloride electrodes, microneedle electrodes, flexible textile electrodes, foam electrodes, and insulated dry electrodes.The conversion mechanisms from ion potential to electronic potential of different biomedical electrodes described in the prior literature are firstly introduced, and then the latest research results concerning the fabrication processes for different biomedical electrodes, and the methods of using them, are reviewed.The advantages and disadvantages of each type of electrode for practical applications are discussed, based on the published literature.A general description of the current applications of biomedical electrodes in ECG, EEG, EMG, and EIT is presented.Typical results from researchers in various countries are reviewed to further introduce the detailed application of different biomedical electrodes.Emerging application fields for biomedical electrodes, such as electrooculography, electrogastrography, and the study of the nervous system, are also presented.Finally, the development and application prospects of biomedical electrodes are described briefly.With the rapid development of microelectronics, micro-nano manufacturing and signal processing technology, the related manufacturing technologies and signal processing methods for biomedical electrodes have achieved great progress; in particular, a much deeper understanding about the contact mechanism with human tissue and skin has been obtained.We believe that many new biomedical electrodes will be developed in the next few years to greatly improve the detection level of bioelectric information.国家自然科学基金(51475397); 厦门大学中央高校基本科研业务费(2013121017)资

IGCT在直流电网中的应用展望

Compared with power electronics systems in AC grid, the power electronics systems in DC grid have a lot of different characteristics, which provide opportunities for the application of integrated gate commutated thyristor (IGCT). This paper timely summarized the development trend of key power electronics systems in DC grid, and the application of IGCT in DC grid is prospected. Firstly, the application characteristics of IGCT and the key power electronics systems, included high-voltage high-power voltage source converter, medium or high-voltage high-power DC transformer and high- voltage high-power dc breaker, in DC grid were introduced. On this basis, by combining nature features of IGCT and voltage source converter, DC transformer and DC breaker, the application opportunities, basic scheme and technology advantages of IGCT in these systems were discussed comprehensively. At last, the problems and research suggestions were given for IGCT to be used in DC grid. The paper has significance to promote voltage conversation and power transfer with high-efficiency, high-density, high- reliability and low-cost in dc grid

基于IGCT的高压大容量模块化多电平变换器

模块化多电平变换器（modularmultilevelconverter,MMC）的多电平调制大幅降低了功率器件开关频率,为集成门极换流晶闸管（integrated gate commutated thyristor,IGCT）的应用带来了契机。该文探讨基于IGCT的高压大容量MMC,尤其是对其拓扑结构、通态和开关行为进行详细分析。在此基础上,对IGCT-MMC的损耗特性进行系统性的分析。文中搭建IGCT-MMC的实验平台,对IGCT-MMC子模块的大电流关断和大功率运行状态进行系统性的测试,验证IGCT-MMC方案的正确性和有效性。该文的研究对推动IGCT在柔性高压直流输电的应用,实现更高电压、更大功率、更高效率和可靠性的柔性直流输电系统具有一定参考价值。Multilevel modulation operation of modular multilevel converter (MMC) reduces switching frequency of power switches greatly, which brings opportunities for application of integrated gate commutated thyristor (IGCT). This paper discussed high-voltage and high-power MMC scheme based on IGCT, and made a detailed analysis on topology, conduction and switching behaviors. Based on this, the performance of power loss of IGCT-MMC was analyzed comprehensively. At last, an experimental platform of IGCT-MMC was built, experimental research of large current switching-off and high power operation was conducted, and the results verified the correctness and effectiveness of IGCT-MMC. The research of the paper has practical significance and scientific value to promote IGCT for application in flexible high voltage direct current transmission (HVDC) and to achieve higher voltage, higher power, higher efficiency and higher reliability of flexible HVDC

Aripiprazole versus other atypical antipsychotics for schizophrenia

BACKGROUND: In most western industrialised countries, second generation (atypical) antipsychotics are recommended as first line drug treatments for people with schizophrenia. In this review we specifically examine how the efficacy and tolerability of one such agent - aripiprazole - differs from that of other comparable second generation antipsychotics. OBJECTIVES: To evaluate the effects of aripiprazole compared with other atypical antipsychotics for people with schizophrenia and schizophrenia-like psychoses. SEARCH METHODS: We searched the Cochrane Schizophrenia Group Trials Register (November 2011), inspected references of all identified studies for further trials, and contacted relevant pharmaceutical companies, drug approval agencies and authors of trials for additional information. SELECTION CRITERIA: We included all randomised clinical trials (RCTs) comparing aripiprazole (oral) with oral and parenteral forms of amisulpride, clozapine, olanzapine, quetiapine, risperidone, sertindole, ziprasidone or zotepine for people with schizophrenia or schizophrenia-like psychoses. DATA COLLECTION AND ANALYSIS: We extracted data independently. For dichotomous data we calculated risk ratios (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis based on a random-effects model. Where possible, we calculated illustrative comparative risks for primary outcomes. For continuous data, we calculated mean differences (MD), again based on a random-effects model. We assessed risk of bias for each included study. MAIN RESULTS: We included 12 trials involving 6389 patients. Aripiprazole was compared to olanzapine, risperidone and ziprasidone. All trials were sponsored by an interested drug manufacturer. The overall number of participants leaving studies early was 30% to 40%, limiting validity (no differences between groups).When compared with olanzapine no differences were apparent for global state (no clinically important change: n = 703, 1 RCT, RR short-term 1.00 95% CI 0.81 to 1.22; n = 317, 1 RCT, RR medium-term 1.08 95% CI 0.95 to 1.22) but mental state tended to favour olanzapine (n = 1360, 3 RCTs, MD total Positive and Negative Syndrome Scale (PANSS) 4.68 95% CI 2.21 to 7.16). There was no significant difference in extrapyramidal symptoms (n = 529, 2 RCTs, RR 0.99 95% CI 0.62 to 1.59) but fewer in the aripiprazole group had increased cholesterol levels (n = 223, 1 RCT, RR 0.32 95% CI 0.19 to 0.54) or weight gain of 7% or more of total body weight (n = 1095, 3 RCTs, RR 0.39 95% CI 0.28 to 0.54).When compared with risperidone, aripiprazole showed no advantage in terms of global state (n = 384, 2 RCTs, RR no important improvement 1.14 95% CI 0.81 to 1.60) or mental state (n = 372, 2 RCTs, MD total PANSS 1.50 95% CI -2.96 to 5.96).One study compared aripiprazole with ziprasidone (n = 247) and both the groups reported similar change in the global state (n = 247, 1 RCT, MD average change in Clinical Global Impression-Severity (CGI-S) score -0.03 95% CI -0.28 to 0.22) and mental state (n = 247, 1 RCT, MD change PANSS -3.00 95% CI -7.29 to 1.29).When compared with any one of several new generation antipsychotic drugs the aripiprazole group showed improvement in global state in energy (n = 523, 1 RCT, RR 0.69 95% CI 0.56 to 0.84), mood (n = 523, 1 RCT, RR 0.77 95% CI 0.65 to 0.92), negative symptoms (n = 523, 1 RCT, RR 0.82 95% CI 0.68 to 0.99), somnolence (n = 523, 1 RCT, RR 0.80 95% CI 0.69 to 0.93) and weight gain (n = 523, 1 RCT, RR 0.84 95% CI 0.76 to 0.94). Significantly more people given aripiprazole reported symptoms of nausea (n = 2881, 3 RCTs, RR 3.13 95% CI 2.12 to 4.61) but weight gain (7% or more of total body weight) was less common in people allocated aripiprazole (n = 330, 1 RCT, RR 0.35 95% CI 0.19 to 0.64). Aripiprazole may have value in aggression but data are limited. This will be the focus of another review. AUTHORS' CONCLUSIONS: Information on all comparisons are of limited quality, are incomplete and problematic to apply clinically. Aripiprazole is an antipsychotic drug with a variant but not absent adverse effect profile. Long-term data are sparse and there is considerable scope for another update of this review as new data emerges from the many Chinese studies as well as from ongoing larger, independent pragmatic trials