Enhancement and assessment of the fundus image / 生物医学工程学杂志

A new enhancement method is proposed based on the characteristics of fundus images in this paper. Firstly, top-hat transform is utilized to weaken the background. Secondly, contrast limited adaptive histogram equalization (CLAHE) is performed to improve the uneven illumination. Finally, two-dimensional matched filters are designed to further enhance the contrast between blood vessels and background. The algorithm was tested in DIARETDB0 databases and showed good applicability for both normal and pathological fundus images. A new no-reference image quality assessment method was used to evaluate the enhancement methods objectively. The results demonstrated that the proposed method could effectively weaken the background, increase contrast, enhance details in the fundus images and improve the image quality greatly.

Study on a new urine analysis core module based on semi-reflection mirror / 生物医学工程学杂志

A new urine analysis core module based on high performance 32-bit microprocessor and high precision color sensor was presented. A novel optical structure and a specific circuit were applied to improve measurement precision and temperature was used to compensate for results in this core module. The information of urine test peice, such as all original data and color RGB value, reflectivity, semi-quantitative level, etc. can be output. The results showed that the measuring precision was about 95% or above with ideal stability and reliability using this presented core module, which can be conveniently applied in various urine analyzers, and can greatly decrease the cost of urine analyzers in development and production.

Objective evaluation of driving fatigue by using variability of pupil diameter under spontaneous pupillary fluctuation conditions / 生物医学工程学杂志

Objective evaluation of driver drowsiness is necessary toward suppression of fatigued driving and prevention of traffic accident. We have developed a new method in which we utilized pupillary diameter variability (PDV) under spontaneous pupillary fluctuation conditions. The method consists of three main steps. Firstly, we use a 90s long infrared video of pupillogram infrared-sensitive CCD camera. Secondly, we employed edge detection algorithm based on curvature characteristics of pupil boundary to extract a set of points of visible pupil boundary, and then we adopted these points to fit a circle to obtain the diameter of the pupil in current frame of video. Finally, the values of PDV in 90s long video is calculated. In an experimental pilot study, the values of PDV of two groups were measured. One group rated themselves as alert (12 men), the other group as sleepy (13 men). The results showed that significant differences could be found between the two groups, and the values were 0.06 +/- 0.005 and 0.141 +/- 0.042, respectively. Taking into account of the knowledge that spontaneous pupillary fluctuation is innervated by autonomic nervous system which activity is known to change in parallel with drowsiness and cannot be influenced by subjective motive of people. From the results of the experiments, we concluded that PDV could be used to evaluate driver fatigue objectively.

Study on the orientation of liquid crystals presented on the glass substrates spin-coated and functionalized with copper ions / 生物医学工程学杂志

A stable, uniform, easily implemented, LC-based chemical and biological sensor substrate for orientations of liquid crystals (LCs) for a long-term is urgently needed for medical applications of the sensors. We proposed a use of spin-coating of copper perchlorate (Cu(ClO4)2), with five different concentrations(0-100mmol/L), directly on glass slides for fabricating a layer of chemically-sensitive copper ions. Observing the transmitted light with a polarized microscope, we found the luminosity of the light propagated through sensors deposited with copper ions started to weaken gradually after a certain time. The higher was the concentration of copper ions covered on the glass substrates of the sensors, the faster the weakening occurred, and the less time was needed for transmitted light to turn completely dark. But there was no change in luminosity of the transmitted light for the sensors without Cu(ClO4)2 spin-coating even after stored at room temperature (25 degrees C) for a whole day. When the Cu(ClO4)2 deposited sensors were stored within a drying oven at room temperature (25 degrees C) for 2 months, it was found that there vas almost no change in luminosity of the transmitted lights. The results showed that all the thin films of LC on glass slides functionalized with Cu(ClO4)2 could keep homeotropic and stable orientation for a long time; the concentration of Cu (ClO4)2I has an influence on the orientation response speed of LC from planar to perpendicular orientation.

Application of superposition theorem in teaching transistor amplifier circuit / 中华医学教育探索杂志

Transistor amplifier is the key and difficult points in the teaching of medical electronics,however,most of the teaching materials on this content is insufficient.Meanwhile,medical students have little knowledge of engineering,so it is difficult for them to grasp the related knowledge.We introduced ‘ superposition theorem’ into the relevant teaching.Teaching practice proved that this reform made it easier for medical students to have an in-depth understanding of the content and better teaching effect was achieved.

Experimental study on a novel affinity adsorbent for removal of endotoxin in plasma / 生物医学工程学杂志

In this paper, the adsorbent properties of Polymyxin B immobilized polystyrene microbeads to remove endotoxin from plasma were studied and the factors that affected the absorption of endotoxin were discussed. The rat models of endotoxemia were established, which were used in hemoperfusion. The experiment results indicated that the novel affinity adsorbent could remove endotoxin from plasma effectively. Moreover, the results also showed that Polymyxin B immobilized polystyrene microbeads was a fine biomaterial of hemoperfusion as well as exhibited a satisfactory blood compatibility.

Development of a piezoelectric sensor for detection of low endotoxin concentration / 生物医学工程学杂志

Endotoxin is an important factor which can lead to endotoxemia and complication. Accurate detection of its concentration is very useful for the diagnosis and treatment of these diseases. A piezoelectric biosensor for detecting endotoxin was developed, which was based on liquid damping effect of quartz crystal resonator. The test results showed that the maximal frequency shift of sensor is linearly dependent on the logarithm value of concentration of endotoxin (0.1 pg/m - 10 ng/ml). The time which d (deltaf)/dt(maax) appeared in frequency shift curve was also linearly dependent on the logarithm value of concentration of endotoxin (0.01 pg/ml - 10 ng/ml). The detection time was shortened and the minimal limit of detection was decreased using the second method. Thus the proposed sensor is much simpler, more precise and has more lower limit of detecting detection of endotoxin when compared with the conventional methods.

Virtual instrumentation and its application to medical DAQ system / 医疗卫生装备

Virtual instrumentation makes great progress in instrument development. LabVIEW is a graphical programming language that uses icons instead of lines of text to create applications. It has been used widely in developing virtual instrument. The application of virtual instrument to medical equipments presented, this paper introduces how to drive common DAQ system and its several implement methods, builds a shared library adapting to AC6010, and develops a low-cost and good-capability DAQ system, which has been utilized to detect biomedical signal with a optic-electric detecting system.