[Research progress on mechanical perturbation in stroke rehabilitation].

Sensorimotor disorder can be easily caused by stroke, and there are many targeted movement rehabilitation therapies. With the development of rehabilitation robot technology, robot-assisted therapy combined with mechanical perturbations has become a more effective motor rehabilitation therapy. In this paper, the definition of mechanical perturbation and its physiological mechanism in stroke rehabilitation are introduced, the research progress on mechanical perturbation in the field of stroke rehabilitation therapy is mainly discussed, the application of mechanical perturbation in motor control, postural response and sensory evaluation of stroke rehabilitation is summarized, and the future development direction of mechanical perturbation rehabilitation therapy is also prospected.

Electrochemical Detection of Ascorbic Acid in Finger-Actuated Microfluidic Chip.

The traditional quantitative analysis methods of ascorbic acid (AA), which require expensive equipment, a large amount of samples and professional technicians, are usually complex and time-consuming. A low-cost and high-efficiency AA detection device is reported in this work. It integrates a three-electrode sensor module prepared by screen printing technology, and a microfluidic chip with a finger-actuated micropump peeled from the liquid-crystal display (LCD) 3D printing resin molds. The AA detection process on this device is easy to operate. On-chip detection has been demonstrated to be 2.48 times more sensitive than off-chip detection and requires only a microliter-scale sample volume, which is much smaller than that required in traditional electrochemical methods. Experiments show that the sample and buffer can be fully mixed in the microchannel, which is consistent with the numerical simulation results wherein the mixing efficiency is greater than 90%. Commercially available tablets and beverages are also tested, and the result shows the reliability and accuracy of the device, demonstrating its broad application prospects in the field of point-of-care testing (POCT).

Dielectrophoretic Separation of Particles Using Microfluidic Chip with Composite Three-Dimensional Electrode.

Integrating three-dimensional (3D) microelectrodes on microfluidic chips based on polydimethylsiloxane (PDMS) has been a challenge. This paper introduces a composite 3D electrode composed of Ag powder (particle size of 10 nm) and PDMS. Ethyl acetate is added as an auxiliary dispersant during the compounding process. A micromachining technique for processing 3D microelectrodes of any shape and size was developed to allow the electrodes to be firmly bonded to the PDMS chip. Through theoretical calculations, numerical simulations, and experimental verification, the role of the composite 3D microelectrodes in separating polystyrene particles of three different sizes via dielectrophoresis was systematically studied. This microfluidic device separated 20-, 10-, and 5-µm polystyrene particles nondestructively, efficiently, and accurately.

[Design and implementation of an automatic analysis system for magnetic resonance quality detection based on QT].

The quality inspection of magnetic resonance imaging (MRI) performance parameters is an important means to ensure the image quality and the reliability of diagnosis results. There are some problems in the manual calculation and eye recognition of the quality inspection parameters, such as strong subjectivity and low efficiency. In view of these facts, an automatic analysis system for MRI quality detection based on QT is proposed and implemented in C++ language. The image processing algorithm is introduced to automatically measure and calculate the quality inspection parameters. The software with comprehensive functions is designed to systematically manage the quality inspection information of MRI. The experimental results show that the automatically calculated parameters are consistent with the manually calculated ones. Accordingly, the accuracy and reliability of the algorithm is verified. The whole system is efficient, convenient and easy to operate, and it can meet the actual needs of MRI quality inspection.

Preparation of giant lipid vesicles with controllable sizes by a modified hydrophilic polydimethylsiloxane microarray chip.

This paper presents an accessible method to prepare giant lipid vesicles (GLVs) with controllable sizes based on the quick formation of patterned lipid films. Lipid solutions naturally penetrate into arrayed micro-apertures on a modified hydrophilic Polydimethylsiloxane (PDMS) chip, and excess lipid films on the surface are removed by a glass slide. Three main factors, the depth and diameter of the micro-apertures and concentration of the lipid solution, were investigated to obtain an optimal preparation condition. Based on this condition, the formed GLVs have a controllable size and narrow size distribution (the standard deviation < 5 µm). By controlling the diameter of the micro-aperture and concentration of the lipid solution, GLVs with various sizes (23, 48, 66 and 82 µm) can be formed.

Non-Uniform Sample Assignment in Training Set Improving Recognition of Hand Gestures Dominated with Similar Muscle Activities.

So far, little is known how the sample assignment of surface electromyogram (sEMG) features in training set influences the recognition efficiency of hand gesture, and the aim of this study is to explore the impact of different sample arrangements in training set on the classification of hand gestures dominated with similar muscle activation patterns. Seven right-handed healthy subjects (24.2 ± 1.2 years) were recruited to perform similar grasping tasks (fist, spherical, and cylindrical grasping) and similar pinch tasks (finger, key, and tape pinch). Each task was sustained for 4 s and followed by a 5-s rest interval to avoid fatigue, and the procedure was repeated 60 times for every task. sEMG were recorded from six forearm hand muscles during grasping or pinch tasks, and 4-s sEMG from each channel was segmented for empirical mode decomposition analysis trial by trial. The muscle activity was quantified with zero crossing (ZC) and Wilson amplitude (WAMP) of the first four resulting intrinsic mode function. Thereafter, a sEMG feature vector was constructed with the ZC and WAMP of each channel sEMG, and a classifier combined with support vector machine and genetic algorithm was used for hand gesture recognition. The sample number for each hand gesture was designed to be rearranged according to different sample proportion in training set, and corresponding recognition rate was calculated to evaluate the effect of sample assignment change on gesture classification. Either for similar grasping or pinch tasks, the sample assignment change in training set affected the overall recognition rate of candidate hand gesture. Compare to conventional results with uniformly assigned training samples, the recognition rate of similar pinch gestures was significantly improved when the sample of finger-, key-, and tape-pinch gesture were assigned as 60, 20, and 20%, respectively. Similarly, the recognition rate of similar grasping gestures also rose when the sample proportion of fist, spherical, and cylindrical grasping was 40, 30, and 30%, respectively. Our results suggested that the recognition rate of hand gestures can be regulated by change sample arrangement in training set, which can be potentially used to improve fine-gesture recognition for myoelectric robotic hand exoskeleton control.

[Design of a Low-power-consuming Magnetoelastic Sensor Detecting System Based on STM32].

Magnetoelastic(ME)sensors,characterized by wireless,passive,low cost and high sensitivity,have widespread applications in various fields.However,its defects of large volume,high power consumption,poor portability and inconveniency for use limit the application prospects of the ME sensors.To solve this problem,the present paper shows a portable,low-power,resonance-type ME sensor detecting system based on STM32.The experimental results indicated that this detecting system allowed the ME sensor to complete the measurement of resonant frequency in different medium and different concentration,with a frequency resolution of less than 1Hz,and the resonant frequency ratio of ME sensors in different sizes 0.933 8,closing the theoretical value of 0.942 3.Moreover,compared with the traditional impedance analyzer combined detecting system and the existing integrated detecting system,the present system has a power consumption of 0.68 Win operation and of only 2.20 mW in the dormancy mode.Therefore,the system can not only replace the original impedance analyzer combined detecting system,but also significantly improve the power control of the existing integrated detecting system,exhibiting the advantages of higher integration,portable measurement,and fine suitability for long-term monitoring.

Impacts of electrical parameters on the electroformation of giant vesicles on ITO glass chips.

A "sandwich" structure device consisted of ITO electrodes and PDMS spacer was designed and used to explore the impact of different electrical parameters (intensity and frequency) on the electroformation of GUVs (giant unilamellar vesicles). Theoretical analysis of the dielectrophoretic effect (DEPE) and the electrohydrodynamic effect (EHE) on the electroformation process indicated that the characteristic frequency of the system could maximize the mutual effect of the both, which might benefit the formation of GUVs. The calculated value of the characteristic frequency (13.3 kHz) was very close to the experimental one (11 kHz). We demonstrated that for a given electroformation system, large amount of well-distributed GUVs can be obtained by optimizing the electrical parameters. In this paper, when choosing the optimal electrical parameters (11 kHz frequency and 5V/mm intensity), the amount of GUVs could reach 65/mm(2), and the diameters of most GUVs (>70%) were 50-70 µm.

Characterization of lipid films by an angle-interrogation surface plasmon resonance imaging device.

Surface topographies of lipid films have an important significance in the analysis of the preparation of giant unilamellar vesicles (GUVs). In order to achieve accurately high-throughput and rapidly analysis of surface topographies of lipid films, a homemade SPR imaging device is constructed based on the classical Kretschmann configuration and an angle interrogation manner. A mathematical model is developed to accurately describe the shift including the light path in different conditions and the change of the illumination point on the CCD camera, and thus a SPR curve for each sampling point can also be achieved, based on this calculation method. The experiment results show that the topographies of lipid films formed in distinct experimental conditions can be accurately characterized, and the measuring resolution of the thickness lipid film may reach 0.05 nm. Compared with existing SPRi devices, which realize detection by monitoring the change of the reflective-light intensity, this new SPRi system can achieve the change of the resonance angle on the entire sensing surface. Thus, it has higher detection accuracy as the traditional angle-interrogation SPR sensor, with much wider detectable range of refractive index.

Responsiveness of voltage-gated calcium channels in SH-SY5Y human neuroblastoma cells on quasi-three-dimensional micropatterns formed with poly (l-lactic acid).

INTRODUCTION: In this study, quasi-three-dimensional (3D) microwell patterns were fabricated with poly (l-lactic acid) for the development of cell-based assays, targeting voltage-gated calcium channels (VGCCs). METHODS AND MATERIALS: SH-SY5Y human neuroblastoma cells were interfaced with the microwell patterns and found to grow as two dimensional (2D), 3D, and near two dimensional (N2D), categorized on the basis of the cells' location in the pattern. The capability of the microwell patterns to support 3D cell growth was evaluated in terms of the percentage of the cells in each growth category. Cell spreading was analyzed in terms of projection areas under light microscopy. SH-SY5Y cells' VGCC responsiveness was evaluated with confocal microscopy and a calcium fluorescent indicator, Calcium Green™-1. The expression of L-type calcium channels was evaluated using immunofluorescence staining with DM-BODIPY. RESULTS: It was found that cells within the microwells, either N2D or 3D, showed more rounded shapes and less projection areas than 2D cells on flat poly (l-lactic acid) substrates. Also, cells in microwells showed a significantly lower VGCC responsiveness than cells on flat substrates, in terms of both response magnitudes and percentages of responsive cells, upon depolarization with 50 mM K(+). This lower VGCC responsiveness could not be explained by the difference in L-type calcium channel expression. For the two patterns addressed in this study, N2D cells consistently exhibited an intermediate value of either projection areas or VGCC responsiveness between those for 2D and 3D cells, suggesting a correlative relation between cell morphology and VGCC responsiveness. CONCLUSION: These results suggest that the pattern structure and therefore the cell growth characteristics were critical factors in determining cell VGCC responsiveness and thus provide an approach for engineering cell functionality in cell-based assay systems and tissue engineering scaffolds.

[Fabrication of three-dimensional microwell patterns and their integration with C17. 2 neural stem cells].

UV photolithography and hydrofluoric acid wet etching were used to produce silicon master molds and polydimethylsiloxane (PMDS)-based soft lithography was adopted to fabricate three-dimensional poly(lactic-co-glycolic acid) (PLGA) and PDMS microwell patterns with high aspect ratio and channel connection. Nine microwell patterns were thus obtained with different structural dimensions. Patterns were treated with oxygen plasma etching and polylysine coating to enhance hydrophilicity and cell compatibility for subsequent culture of C17. 2 neural stem cells. With proliferation during the culture, C17. 2 cells gradually distributed within the microwells, showing an obviously three-dimensional (3-D) growth behavior. The presence of channel structures greatly favored the 3-D growth of C17. 2 neural stem cells on the microwell patterns. Multi-layered scanning with confocal microscopy and 3-D rendering after carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) staining showed that most C17. 2 cells grew within a range of 30 to 90 microm from the microwell bottom. Immunofluorescence staining indicated that C17. 2 cells within 3-D microwell patterns were uniformly nestin-positive on day 2 after cell plating. It could well be concluded that the microwell patterns thus fabricated were suitable for the 3-D culture and subsequent differentiation of C17. 2 neural stem cells. And the cells can be maintained with uniform stemness properties while cultured in these microwell patterns.

[The study of active noise control method for noisy surgery tools].

Noise problem is encountered in many types of surgery, especially in orthopaedic surgery, where the cutting tool and its actuation part such as motor always generates big noise. This work is dedicated to developing a novel and promising solution based on the active noise control (ANC) technology to solve the noise problem in an orthopaedic theatre. The development process began with building an engineering evaluation model (EEM) to analyze the specifics of sound interactions and sound field involved in the noise problem. This model can describe the acoustic problem in a straightforward way, help to design a good control system and furthermore to assess the result and to optimize the control structure. Then the "auto position tracking near head space ANC" strategy was proposed from the model study. Furthermore, the real sound field measurement experiment proved the possibility of proposed design.

Microfluidic pool structure for cell docking and rapid mixing.

A microfluidic pool structure for cell docking and rapid mixing is described. The pool structure is defined as a microchamber on one structural layer of a bilayer chip and connects with two or more individual microchannels on the other structural layer. In contrast to the turbulent flow in a macroscale pool, laminar streams enter and exit this microfluidic pool structure with definite and controllable direction that may be influenced by the location and geometry of the pool. A simple microfluidic model was used to validate this hypothesis. In this model, a microscale pool structure was made on the lower layer of a chip and connected with three parallel microchannels in the upper layer. Simulation and experimental results indicated that the flow profile within the pool structure was determined by its geometry and location. This could be used as a flow control method and it was simpler than designs based on microvalve, hydraulic pressure, or electrokinetic force, and has some important applications. For example, controllable streams within this structure were used to immobilize biological cells along the microchannel walls. When different solution streams flowed through the pool, rapid diffusion of analytes occurred for short diffusion distance between vertical flow laminas. Furthermore, desired dilution (mixing) ratio could be obtained by controlling the geometry of the microfluidic pool.

[Development of the chip system for measurement of red blood cell rheology].

We have developed a novel silicon microchannel system for the research of the red blood cell rheology and deformation. Recurring to many kinds of information technologies and advanced test means such as the electronic microscope, the image acquisition system and the computer processing system and by using the up-to-date Micro Electro Mechanical System (MEMS) technology, a new measuring system of red bood cell deformation is designed based on the chip and a model using the silicon microchannel to simulate capillary vessel network. It provides a real-time collection and anaysis of data which include image, speed, flow parameter, and so on. It provides printing, storage of the analysis results and patients' database management.