Numerical model of shear module of alginate micro-beads under ultrasonic thermal effect / 军事医学

Objective To establish a numerical model of the shear module of alginate beads stimulated by ultrasonic sound.Methods The compression ratio and force of alginate beads were recorded with the compression test .The shear module of beads was measured with a Hertz model .When to alginate beads were stimulated ultrasonically for different durations , the ultrasonic stimulation power , ultrasonic pulse ratio , and changes in the shear module and solution temperature were measured.Results Temperatures in the solution and shear module of alginate beads increased under different ultrasonic stimulation conditions .Modeling analysis revealed the relationship between the shear module of alginate beads and the corresponding temperature .The shear module of beads was in a quadratic equation with temperature (20℃

Improvement in EIS diagnosis accuracy using a multi-frequency parameter analysis method: preliminary results.

In this work we assessed the validity of the multi-frequency parameter (MFP) analysis method in distinguishing EIS false positive results. We chose 15 subjects with invasive duct carcinoma as the control group in which EIS results were all positive. In the experiment, three test groups-the Contact, the Skin and the Horm groups-were set to correspond to three common types of EIS false results. In the Contact group, false positive results were induced by poor contact of the measuring probe. In the Skin group, false positive results were induced by skin ridges. In the Horm group, false positive results were induced by a high hormone level. Based on the MFP analysis method, we obtained the Cole-Cole parameters of each subject in the control group and the test groups. Statistical analyses showed there was a significant difference in G(0N), G(infinity)N) or alpha(N) between the control group and the Contact or the Skin group. A significant difference between the control group and the Horm group existed only in alpha(N). These results suggested that by means of the MFP analysis method it was possible to distinguish between a false positive result and a positive result caused by breast cancer. In conclusion, the MFP analysis method appears to be a feasible means to improve the diagnosis accuracy of EIS for breast cancer detection.

Breast cancer detection based on multi-frequency EIS measurement.

As a convenient, un-injurious and low cost method for women breast tumor diagnosis, Electrical Impedance Scanning (EIS) is being paid increasing attention. But EIS still has some problems. In theory the malignant tumor has higher electrical conductivity than normal tissue and benign tumor, so the cancer will be recognized in the EIS image as a bright spot. However, in practical the difference is not so obvious. In many cases it is difficult to judge whether a suspicious bright spot tells a malignant or benign tumor. This paper concerns a new method based on multi-frequency EIS measurement to solve this problem. A group of scanning results with various stimulating frequencies will be performed during an EIS measurement, which is automatically controlled by specially designed device and the location and pressure of the sensor will keep stable, so we will get a series of data at different stimulating frequencies through a measurement. Because the malignant and the benign tumor have different curves in electrical conductivity-frequency diagram, we can analyze the data at every frequency and find out the attribute of the tumor. Clinical trails have been carried out. Subjects were suspicious sufferers that were to receive histopathology examinations, and all analyses have been compared with histopathology results.

Study of influencing factors on Electrical Impedance Scanning Imaging.

Electrical impedance scanning (EIS) is a new adjunctive diagnostic method for women breast cancer examination. In clinic research, we found some influencing factors which can induce a bad EIS imaging results. In order to analyze the influencing factors on EIS imaging and find the solutions, we set up an EIS workbench which can simulate the influencing factors that may happen in a clinic. We studied the influencing factors from size, depth of the target; the influence from the poor contact; the influence from the unparallel current field. The experiment results show that the detectability of EIS system is a function of the depth, the size and the area of electrodes; a good contact between the probe and the skin can decrease the artificial imaging; using the imaging algorithm can calibrate the imaging induced by unparallel current field.

Frequency characteristic of diseased breast tissues detected by electrical impedance scanning / 生物医学工程学杂志

The rules of conductance parameters on diseased breast tissue, which change with the driven frequency, are studied by use of electrical impedance scanning. This work is intended to provide a basis for further examination of breast. We have obtained conductance parameters' frequency characteristic of three kinds of breast diseases, i.e. invasive ductal carcinoma, neoplastic hyperplasia, and mastopathia. And by comparison, we find that the frequency characteristic of the diseased breast tissues is different from that of the peripheral normal tissues, and the frequency characteristic shows differences among the three kinds of diseased breast tissues. So, we are able to identify the kind of breast disease by its frequency characteristic.

A bipolar optocoupler isolation amplifier with high precision and wide bandwidth / 生物医学工程学杂志

To fit the technological requirements in electrical impedance tomography system, an improved bipolar optocoupler isolation amplifier based on single analog optocoupler was realized. The experimental results illustrates that the full power -3dB bandwidth of this circuit is greater than 800 KHz, the equivalent output noise is lower than 50 uV(RMS), and the linearity at +/- 4 V inputs is lower than 0.01%. In addition to these features, the circuit also have the advantages of simple structure and no distortion caused by mismatch between analog optocouplers.