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Gu X.N.,Peking University | Gu X.N.,Beihang University | Xie X.H.,Chinese University of Hong Kong | Xie X.H.,Soochow University of China | And 4 more authors.
Acta Biomaterialia | Year: 2012

Magnesium alloys have shown potential as biodegradable metallic materials for orthopedic applications due to their degradability, resemblance to cortical bone and biocompatible degradation/corrosion products. However, the fast corrosion rate and the potential toxicity of their alloying element limit the clinical application of Mg alloys. From the viewpoint of both metallurgy and biocompatibility, strontium (Sr) was selected to prepare hot rolled Mg-Sr binary alloys (with a Sr content ranging from 1 to 4 wt.%) in the present study. The optimal Sr content was screened with respect to the mechanical and corrosion properties of Mg-Sr binary alloys and the feasibility of the use of Mg-Sr alloys as orthopedic biodegradable metals was investigated by in vitro cell experiments and intramedullary implantation tests. The mechanical properties and corrosion rates of Mg-Sr alloys were dose dependent with respect to the added Sr content. The as-rolled Mg-2Sr alloy exhibited the highest strength and slowest corrosion rate, suggesting that the optimal Sr content was 2 wt.%. The as-rolled Mg-2Sr alloy showed Grade I cytotoxicity and induced higher alkaline phosphatase activity than the other alloys. During the 4 weeks implantation period we saw gradual degradation of the as-rolled Mg-2Sr alloy within a bone tunnel. Micro-computer tomography and histological analysis showed an enhanced mineral density and thicker cortical bone around the experimental implants. Higher levels of Sr were observed in newly formed peri-implant bone compared with the control. In summary, this study shows that the optimal content of added Sr is 2 wt.% for binary Mg-Sr alloys in the rolled state and that the as-rolled Mg-2Sr alloy in vivo produces an acceptable host response. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Zhang J.,University of Bristol | Meng L.,CAS Shenzhen Institute of Biomedical and Health Engineering | Cai F.,CAS Shenzhen Institute of Biomedical and Health Engineering | Zheng H.,CAS Shenzhen Institute of Biomedical and Health Engineering | Courtney C.R.P.,University of Bath
Applied Physics Letters | Year: 2014

Standing surface acoustic waves (SAWs) and standing bulk waves (BWs) are combined to pattern two populations of particles with differing sizes. Patterns with large differences in wavelength in each direction and simultaneous generation of different patterns for each population are demonstrated. Particles are trapped at nodal positions of orthogonal standing wave fields in patterns determined by device voltage amplitudes and frequencies. 10-μm beads are trapped at points at the intersection of the pressure nodes of the SAW and BW fields, and 1-μm beads are trapped in lines at the pressure nodes of the SAW field, producing a multi-scale pattern.


Wang J.,CAS Shenzhen Institute of Biomedical and Health Engineering | Tang J.,CAS Shenzhen Institute of Biomedical and Health Engineering | Zhang P.,CAS Shenzhen Institute of Biomedical and Health Engineering | Li Y.,Guangdong Innovation Team for Biodegradable Magnesium and Medical Implants | And 3 more authors.
Journal of Biomedical Materials Research - Part B Applied Biomaterials | Year: 2012

As a bioabsorbable metal with mechanical properties close to bone, pure magnesium or its alloys have great potential to be developed as medical implants for clinical applications. However, great efforts should be made to avoid its fast degradation in vivo for orthopedic applications when used for fracture fixation. Therefore, how to decease degradation rate of pure magnesium or its alloys is one of the focuses in Research and Development (R&D) of medical implants. It has been recognized that surface modification is an effective method to prevent its initial degradation in vivo to maintain its desired mechanical strength. This article reviews the recent progress in surface modifications for prevention of fast degradation of magnesium or its alloys using in vitro testing model, a fast yet relevant model before moving towards time-consuming and expensive in vivo testing. Pros and cons of various surface modifications are also discussed for the goal to design available products to be applied in clinical trials. © 2012 Wiley Periodicals, Inc.


Zhou Q.,University of Southern California | Lam K.H.,Hong Kong Polytechnic University | Zheng H.,CAS Shenzhen Institute of Biomedical and Health Engineering | Qiu W.,CAS Shenzhen Institute of Biomedical and Health Engineering | Shung K.K.,University of Southern California
Progress in Materials Science | Year: 2014

Piezoelectric single crystals, which have excellent piezoelectric properties, have extensively been employed for various sensors and actuators applications. In this paper, the state-of-art in piezoelectric single crystals for ultrasonic transducer applications is reviewed. Firstly, the basic principles and design considerations of piezoelectric ultrasonic transducers will be addressed. Then, the popular piezoelectric single crystals used for ultrasonic transducer applications, including LiNbO3 (LN), PMN-PT and PIN-PMN-PT, will be introduced. After describing the preparation and performance of the single crystals, the recent development of both the single-element and array transducers fabricated using the single crystals will be presented. Finally, various biomedical applications including eye imaging, intravascular imaging, blood flow measurement, photoacoustic imaging and microbeam applications of the single crystal transducers will be discussed. © 2014 Elsevier Ltd. All rights reserved.


Meng L.,CAS Shenzhen Institute of Biomedical and Health Engineering | Cai F.,CAS Shenzhen Institute of Biomedical and Health Engineering | Chen J.,CAS Shenzhen Institute of Biomedical and Health Engineering | Niu L.,CAS Shenzhen Institute of Biomedical and Health Engineering | And 3 more authors.
Applied Physics Letters | Year: 2012

A microfluidic device is developed to transport microbubbles (MBs) along a desired trajectory in fluid by introducing the phase-shift to a planar standing surface acoustic wave (SSAW). The radiation force of SSAW due to the acoustic pressure gradient modulated by a phase-shift can move MBs to anticipated potential wells in a programmable manner. The resolution of the transportation is approximately 2.2 μm and the estimated radiation force on the MBs is on the order of 10 -9 N. This device can be used for manipulation of bioparticles, cell sorting, tissue engineering, and other biomedical applications. © 2012 American Institute of Physics.


Zheng W.,CAS Shenzhen Institute of Biomedical and Health Engineering
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2014

Multilabeling which maps the distribution of different targets is an indispensable technique in many biochemical and biophysical studies. Two-photon excitation fluorescence (TPEF) microscopy of endogenous fluorophores combining with conventional fluorescence labeling techniques such as genetically encoded fluorescent protein (FP) and fluorescent dyes staining could be a powerful tool for imaging living cells. However, the challenge is that the excitation and emission wavelength of these endogenous fluorophores and fluorescent labels are very different. A multi-color ultrafast source is required for the excitation of multiple fluorescence molecules. In this study, we developed a two-photon imaging system with excitations from the pump femtosecond laser and the selected supercontinuum generated from a photonic crystal fiber (PCF). Multiple endogenous fluorophores, fluorescent proteins and fluorescent dyes were excited in their optimal wavelengths simultaneously. A time- and spectral-resolved detection system was used to record the TPEF signals. This detection technique separated the TPEF signals from multiple sources in time and wavelength domains. Cellular organelles such as nucleus, mitochondria, microtubule and endoplasmic reticulum, were clearly revealed in the TPEF images. The simultaneous imaging of multiple fluorophores of cells will greatly aid the study of sub-cellular compartments and protein localization. © 2014 SPIE.


Hu D.,CAS Shenzhen Institute of Biomedical and Health Engineering | Sheng Z.,Huazhong Agricultural University | Gong P.,CAS Shenzhen Institute of Biomedical and Health Engineering | Zhang P.,CAS Shenzhen Institute of Biomedical and Health Engineering | Cai L.,CAS Shenzhen Institute of Biomedical and Health Engineering
Analyst | Year: 2010

In this paper, we report a new homogeneous assay for rapid, highly selective and sensitive detection of Hg2+ in aqueous solution based on the induced photoluminescence (PL) quenching of BSA-modified gold nanoclusters (BSA-Au NCs). There was a linear correlation between the expression (I0 - I)/I0 and the concentrations of Hg2+ over the ranges of 0.4-43.2 μM, and the corresponding limit of detection (LOD) was 80 nM. The relative standard deviation of 5 replicate measurements was 1.4% for 1.0 × 10-5 mol L-1 Hg2+. Moreover, this method has excellent selectivity over metal ions and anions. The feasibility of the BSA-Au NCs sensor for Hg2+ in different aqueous samples was demonstrated with satisfactory results. Moreover, the possible sensing Hg2+ mechanism was also discussed. © The Royal Society of Chemistry 2010.


Li S.,CAS Shenzhen Institute of Biomedical and Health Engineering | Huang J.,CAS Shenzhen Institute of Biomedical and Health Engineering | Cai L.,CAS Shenzhen Institute of Biomedical and Health Engineering
Nanotechnology | Year: 2011

A porous silicon microcavity (PSM) is highly sensitive to subtle interface changes due to its high surface area, capillary condensation ability and a narrow resonance peak (∼10nm). Based on the well-defined optical properties of a PSM, we successfully fabricated a bacteria detection chip for molecular or subcellular analysis by surface modification using undecylenic acid (UA), and the specific recognition binding of vancomycin to the D-alanyl-D-alanine of bacteria. The red shift of the PSM resonance peak showed a good linear relationship with bacteria concentration ranging from 100 to 1000bacteriaml - 1 at the level of relative standard deviation of 0.994 and detection limit of 20bacteriaml- 1. The resulting PSM sensors demonstrated high sensitivity, good reproducibility, fast response and low cost for biosensing. © IOP Publishing Ltd.


Liu G.Z.,CAS Shenzhen Institute of Biomedical and Health Engineering
Telemedicine journal and e-health : the official journal of the American Telemedicine Association | Year: 2011

Wearable medical devices have enabled unobtrusive monitoring of vital signs and emerging biofeedback services in a pervasive manner. This article describes a wearable respiratory biofeedback system based on a generalized body sensor network (BSN) platform. The compact BSN platform was tailored for the strong requirements of overall system optimizations. A waist-worn biofeedback device was designed using the BSN. Extensive bench tests have shown that the generalized BSN worked as intended. In-situ experiments with 22 subjects indicated that the biofeedback device was discreet, easy to wear, and capable of offering wearable respiratory trainings. Pilot studies on wearable training patterns and resultant heart rate variability suggested that paced respirations at abdominal level and with identical inhaling/exhaling ratio were more appropriate for decreasing sympathetic arousal and increasing parasympathetic activities.


Cao C.Z.,CAS Shenzhen Institute of Biomedical and Health Engineering
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

The security of Body Sensor Network (BSN) has become a vital concern, as the massive development of BSN applications in healthcare. A family of biometrics based security methods has been proposed in the last several years, where the bio-information derived from physiological signals is used as entity identifiers (EIs) for multiple security purposes, including node recognition and keying material protection. Among them, a method named as Physiological Signal based Key Agreement (PSKA) was proposed to use frequency-domain information of physiological signals together with Fuzzy Vault scheme to secure key distribution in BSN. In this study, the PSKA scheme was firstly analyzed and evaluated for its practical usage in terms of fuzzy performance, the result of which indicates that the scheme is not as good as claimed. An improved scheme with the deployment of Fuzzy Vault and error correcting coding was then proposed, followed by simulation analysis. The results indicate that the improved scheme is able to improve the performance of Fuzzy Vault and thus the success rate of authentication or key distribution between genuine nodes of a BSN.

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