Transcranial direct current stimulation (tDCS) is a brain stimulation intervention technique, which has the problem of different criteria for the selection of stimulation parameters. In this study, a four-layer real head model was constructed. Based on this model, the changes of the electric field distribution in the brain with the current intensity, electrode shape, electrode area and electrode spacing were analyzed by using finite element simulation technology, and then the optimal scheme of electrical stimulation parameters was discussed. The results showed that the effective stimulation region decreased and the focusing ability increased with the increase of current intensity. The normal current density of the quadrilateral electrode was obviously larger than that of the circular electrode, which indicated that the quadrilateral electrode was more conducive to current stimulation of neurons. Moreover, the effective stimulation region of the quadrilateral electrode was more concentrated and the focusing ability was stronger. The focusing ability decreased with the increase of electrode area. Specifically, the focusing tended to increase first and then decrease with the increase of electrode spacing and the optimal electrode spacing was 64.0–67.2 mm. These results could provide some basis for the selection of electrical stimulation parameters.
ObjectivesThis study aimed to study the economic effect of five kinds of detection systems for nucleic acid, which were based on five kinds of working electrodes: gold electrode, glassy carbon electrode, carbon paste electrode, screen printing electrode, and indium-tin-oxide (ITO) glass electrode.MethodsThe cost of completing a single test was taken as the cost of economic analysis. The Youden index was used to represent the effect of cost-effectiveness analysis (CEA). Meanwhile, the cost-utility analysis (CUA) and incremental cost-effectiveness ratio (ICER) were used for the economic analysis of the corresponding system.ResultsThe cost of five detection systems based on gold electrode, glass carbon electrode, carbon paste electrode, screen printing electrode, and ITO glass electrode was 3.70 yuan/unit, 4.20 yuan/unit, 5.25 yuan/unit, 33.98 yuan/unit and 5.01 yuan/unit, respectively. The Youden indexes of all five systems were 1. The cost effectiveness (C/E) were 3.70, 4.20, 5.25, 33.98, and 5.01, respectively. The cost utility (C/U) were 6.61, 6.89, 9.91, 62.93, and 9.45, respectively. The C'/E and C'/U of the gold electrode detection system were the minimum (2.96 and 5.29). Compared with the system applying the gold electrode, the system using the glassy carbon electrode had ΔC >0 and ?E0 >0; When carbon paste electrode, screen printing electrode, and ITO glass electrode system were used, ?C was >0 and ?E0 was <0.ConclusionsFrom the perspective of CEA and CUA, the system using the gold electrode has the best economic effect. The sensitivity analysis proved the reliability of CEA and CUA results. According to the ICER, gold electrode or glassy carbon electrode can be used in clinical practice with the choice depending on the user.
ObjectiveThe purpose of this study was to compare the value of SEEG and subdural cortical electrodes monitoring in preoperative evaluation of epileptogenic zone.
MethodsFeatures of patients using SEEG (48 cases) and subdural cortical electrodes monitoring (52 cases) to evaluate the epileptogenic zone were collected from June 2011 to June 2015. And the evaluation results, surgical effects and complications were compared.
ResultsThere was no significant difference between SEEG and subdural cortical electrodes monitoring in identifying the epileptogenic zone or taking epileptic surgery, but SEEG could monitor multifocal and bilateral epileptogenic zone. And there was no significant difference in postoperative seizure control and intelligence improvement (P > 0.05). The total complication rate of SEEG was lower than subdural cortical electrodes monitoring, especially in hemorrhage and infection (P < 0.05).
ConclusionsThere was no difference among SEEG and subdural cortical electrodes monitoring in surgical results, but SEEG with less hemorrhagic and infectious risks. SEEG is a safe and effective intracranial monitoring method, which can be widely used.
In order to reduce the mortality rate of cardiovascular disease patients effectively, improve the electrocardiogram (ECG) accuracy of signal acquisition, and reduce the influence of motion artifacts caused by the electrodes in inappropriate location in the clothing for ECG measurement, we in this article present a research on the optimum place of ECG electrodes in male clothing using three-lead monitoring methods. In the 3-lead ECG monitoring clothing for men we selected test points. Comparing the ECG and power spectrum analysis of the acquired ECG signal quality of each group of points, we determined the best location of ECG electrodes in the male monitoring clothing. The electrode motion artifacts caused by improper location had been significantly improved when electrodes were put in the best position of the clothing for men. The position of electrodes is crucial for ECG monitoring clothing. The stability of the acquired ECG signal could be improved significantly when electrodes are put at optimal locations.
In order to accurately localize the image coordinates and serial numbers of intraoperative subdural matrix electrodes, a matrix electrode localization algorithm for image processing is proposed in this paper. Firstly, by using point-by-point extended electrode location algorithm, the electrode is expanded point-by-point vertically and horizontally, and the initial coordinates and serial numbers of each electrode are determined. Secondly, the single electrode coordinate region extraction algorithm is used to determine the best coordinates of each electrode, so that the image coordinates and serial numbers of all electrodes are determined point-by-point. The results show that the positioning accuracy of electrode serial number is 100%, and the electrode coordinate positioning error is less than 2 mm. The algorithms in this paper can accurately localize the image coordinates and the serial numbers of a matrix electrode arranged in an arc, which could aid drawing of cortical function mapping, and achieve precise positioning of brain functional areas, so that it can be widely used in neuroscience research and clinical application based on electrocorticogram analysis.
ObjectiveTo evaluate the application of stereotactic electrode implantation on precise epileptogenic zone localization.
MethodRetrospectively studied 140 patients with drug-resist epilepsy from March 2012 to June 2015, who undergone a procedure of intracranial stereotactic electrode for localized epileptogenic zone.
ResultsIn 140 patients who underwent the ROSA navigated implantation of intracranial electrode, 109 are unilateral implantation, 31 are bilateral; 3 patients experienced an intracranial hematoma caused by the implantation. Preserved time of electrodes, on average, 8.4days (range 2~35 days); Obseved clinical seizures, on average, 10.8 times per pt (range 0~98 times); There were no cerebrospinal fluid leak, intracranial hematoma, electrodes fracture or patient death, except 2 pt's scalp infection (1.43%, scalp infection rate); 131 pts' seizure onset area was precisely localized; 71 pts underwent SEEG-guide resections and were followed up for more than 6 months. In the group of 71 resection pts, 56 pts were reached Engel I class, 2 were Engel Ⅱ, 3 was Engel Ⅲ and 10 were Engel IV class.
ConclusionTo intractable epilepsy, when non-invasive assessments can't find the epileptogenic foci, intracranial electrode implantation combined with long-term VEEG is an effective method to localize the epileptogenic foci, especially the ROSA navigated stereotactic electrode implantation, which is a micro-invasive, short-time, less-complication, safe-guaranteed, and precise technique.
In order to solve the problems of insufficient stimulation channels and lack of stimulation effect feedback in the current electrical stimulation system, a functional array electrode electrical stimulation system with surface electromyography (sEMG) feedback was designed in this paper. Firstly, the effectiveness of the system was verified through in vitro and human experiments. Then it was confirmed that there were differences in the number of amperage needed to achieve the same stimulation stage among individuals, and the number of amperage required by men was generally less than that of women. Finally, it was verified that the current required for square wave stimulation was smaller than that for differential wave stimulation if the same stimulation stage was reached. This system combined the array electrode and sEMG feedback to improve the accuracy of electrical stimulation and performed the whole process recording of feedback sEMG signal in the process of electrical stimulation, and the electrical stimulation parameters could change with the change of the sEMG signal. The electrical stimulation system and sEMG feedback worked together to form a closed-loop electrical stimulation working system, so as to improve the efficiency of electrical stimulation rehabilitation treatment. In conclusion, the functional array electrode electrical stimulation system with sEMG feedback developed in this paper has the advantages of simple operation, small size and low power consumption, which lays a foundation for the introduction of electrical stimulation rehabilitation treatment equipment into the family, and also provides certain reference for the development of similar products in the future.
As an interface between external electronic devices and internal neural nuclei, microelectrodes play an important role in many fields, such as animal robots, deep brain stimulation and neural prostheses. Aiming at the problem of high price and complicated fabrication process of microelectrode, a microelectrode twisting machine based on open source electronic prototyping platform (Arduino) and three-dimensional printing technology was proposed, and its microelectrode fabrication performance and neural stimulation performance were verified. The results show that during the fabrication of microelectrodes, the number of positive twisting turns of the electrode wire should generally be set to about 1.8 times of its length, and the number of reverse twisting rings is independent of the length, generally about 5. Moreover, compared with the traditional instrument, the device is not only inexpensive and simple to manufacture, but also has good expandability. It has a positive significance for both the personalization and popularization of microelectrode fabrication and the reduction of experimental cost.
The injury of the knee joint is usually accompanied with the generation of hydrops. The volume of hydrops can be used as a reference to evaluate the extent of knee joint injuries. Based on the principle of bioimpedance detection, in this paper, a new method is proposed to detect knee joint hydrops. Firstly, a three-dimensional model of the knee joint was established according to the physiological and anatomical structure of the knee joint. Secondly, a knee impedance detection system was constructed based on the four-electrode theory, and the relationship between the knee impedance change and the volume of hydrops was calculated by linear regression. Finally, the model of rat knee joint hydrops was established, and the knee joint impedance was measured under different hydrops content to deduce the relationship between the fluid content and the knee joint impedance. The fluid volume in the joint was calculated by measuring the knee joint impedance, and the error rate was less than 10%. The experimental results show that the method proposed in this paper can establish the relationship between the impedance of the knee and the volume of fluid and realize the detection of the fluid volume.
Tumor treating fields (TTF) therapy is an innovative tumor treatment modality. Currently, the TTF devices predominantly employ insulated ceramic electrodes as the electric field transmission medium, resulting in low energy transfer efficiency of the electric field and poor portability of the devices. This study proposed an innovative TTF transmission mode and independently designed a conducted-electrode TTF cell culture dish utilizing inert titanium materials. The electric field conduction characteristics were verified through finite element simulations and experimental tests. Finally, based on the self-manufactured conducted-electrode TTF cell culture dish, experiments on the proliferation inhibition of U87 tumor cells by TTF were conducted. The results demonstrated that under an applied TTF voltage of 10 V and frequency of 200 kHz, the electric field intensities within the medium for conducted and insulated electrodes are approximately 2.5 V/cm and 0.7 V/cm, respectively. Compared to conventional insulated TTF systems, the conducted-electrode TTF configuration exhibited a lower electrode voltage drop and a higher electric field intensity in the culture medium, indicating superior electric field transmission efficiency. Following 36 hours of treatment with conducted-electrode TTF on U87 cells, the proliferation inhibition rate reached approximately 50%, demonstrating effective suppression of tumor cell growth. This approach presents a potential direction for optimizing TTF treatment modality and device design.
