Lu Xiaoying

The underlying biological mechanisms of biocompatibility differences between bare and TiN-coated NiTi alloys.

TiN coating has been demonstrated to improve the biocompatibility of bare NiTi alloys; however, essential biocompatibility differences between NiTi alloys before and after TiN coating are not known so far. In this study, to explore the underlying biological mechanisms of biocompatibility differences between them, the changes of bare and TiN-coated NiTi alloys in surface chemical composition, morphology, hydrophilicity, Ni ions release, cytotoxicity, apoptosis, and gene expression profiles were compared using energy-dispersive spectroscopy, scanning electron microscopy, contact angle, surface energy, Ni ions release analysis, the methylthiazoltetrazolium (MTT) method, flow cytometry and microarray methods, respectively. Pathways binding to networks and real-time polymerase chain reaction (PCR) were employed to analyze and validate the microarray data, respectively. It was found that, compared with the bare NiTi alloys, TiN coating significantly decreased Ni ions content on the surfaces of the NiTi alloys and reduced the release of Ni ions from the alloys, attenuated the inhibition of Ni ions to the expression of genes associated with anti-inflammatory, and also suppressed the promotion of Ni ions to the expression of apoptosis-related genes. Moreover, TiN coating distinctly improved the hydrophilicity and uniformity of the surfaces of the NiTi alloys, and contributed to the expression of genes participating in cell adhesion and other physiological activities. These results indicate that the TiN-coated NiTi alloys will help overcome the shortcomings of NiTi alloys used in clinical application currently, and can be expected to be a replacement of biomaterials for a medical device field.

Study of microelectronics for detecting and stimulating of central neural signals

Test circuits for the signal detection and the function electrical stimulation (FES) of neurons have been designed, implemented at first by using discrete devices and characterized off-body. The detecting circuit consisting of three-stage operational amplifiers has a controllable gain up to 10/sup 5/, a -3 dB bandwidth of 30 kHz, and an equivalent input noise of about 9 nV//spl radic/Hz. The FES circuit consisting of two-stage operational amplifiers has a bandwidth of more than 10 kHz and a variable gain from 20 dB to 60 dB can provide a current of more than 1 mA to a load of 10 k/spl Omega/ They are intended to connect with both cuff-type and staff-type microelectrodes. Integrated circuits (IC) for the neural signal process have been designed with features of low voltage and low power. A more biocompatible composite has been synthesized to modify the silicon and related material.

A multichannel neural signal detecting module： Its design and test in animal experiments

Abstract A four-channel neural signal detecting module with an implantable 12-contact cuff electrode was designed for real-time neural signal recording on peripheral and central nerves. The mathematic coupling model between nerve and electronic system was analyzed. Electrode connection configurations were considered. The detecting circuit included an input coupling network, a pre-amplifier, and some filtering and notching stages. Shield guarding and the right-leg-driven circuit were developed for further climination of common mode interference. By electrode switches, the module could cooperate with a nerve functional electrical stimulation circuit, building a neural channel bridge-connection system. It was tested by recording experiments on rats sciatic and spine nerves. The signals is spontaneous and evoked conditions have been captured successfully. In addition, an implantable neural signal detecting CMOS IC has been introduced. *Supported by National Natural Science Foundation of China (Grant Nos. 698...

Natural hydroxyapatite/chitosan composite for bone substitute materials

We developed the natural hydroxyapatite/chitosan composite that could be molded into any desired shape. The powder component consists of natural hydroxyapatite, which is epurated from bone of pigs. The liquid component consists of malic acid and chitosan. To study the possibility of the composite on repairing bone defects, 15 white rabbits were each operated on left tibias to create two square bone defects. One of the defects was reconstructed with the composite; the other was not repaired as a blank control. 3 of the animals were killed at the end of 2 weeks, 4 weeks, 8 weeks, 12 weeks and 16 weeks respectively to be evaluated with anatomy and histology. No apparent reject reaction was found, except for a mild inflammatory infiltrate found at postoperative 2 weeks. Fibrous tissue became thinner at postoperative 2-8 weeks and bony connection was partly shown at postoperative 12 weeks. The new bone was the same as the recipient bone at postoperative 16 weeks. The hydroxyapatite/chitosan composite has good biocompatibility and osteoconduction. It is a potential repairing material for clinical application

Design and experiment of a neural signal detection using a FES driving system

The channel bridging, signal regenerating, and functional rebuilding of injured nerves is one of the most important issues in life science research. In recent years, some progresses in the research area have been made in repairing injured nerves with microelectronic neural bridge. Based on the previous work, this paper presents a neural signal detection and functional electrical stimulation (FES) driving system with using high performance operational amplifiers, which has been realized. The experimental results show that the designed system meets requirements. In animal experiments, sciatic nerve signal detection, regeneration and function rebuilding between two toads have been accomplished successfully by using the designed system.

A four-channel microelectronic system for neural signal regeneration

This paper presents a microelectronic system which is capable of making a signal record and functional electric stimulation of an injured spinal cord. As a requirement of implantable engineering for the regeneration microelectronic system, the system is of low noise, low power, small size and high performance. A front-end circuit and two high performance OPAs (operational amplifiers) have been designed for the system with different functions, and the two OPAs are a low-noise low-power two-stage OPA and a constant-gm RTR input and output OPA. The system has been realized in CSMC 0.5-μm CMOS technology. The test results show that the system satisfies the demands of neuron signal regeneration.

Primary study on the electric signal transmission characteristics of human Meridians on skin surface

As one of the basic concepts of the Chinese medicine, the theory of Meridians and Collaterals is lack of scientific demonstration so far. In order to verify the existence of Meridians and Collaterals, a method based on the electric technique and information theory is suggested, A specialized electrode array has been designed and an experimental scheme of signal stimulating and detecting was introduced. The response signals at different points on skin surface were analyzed. A difference between the signal amplitudes along a Meridian and on its sides was found. The study on Meridian based on the electric technique and information theory is one of the important fields of bioelectronics.

Study on Si-surface modification with chitosan and cell adhesion

Chitoan was immobilized on silicon surface by(3-aminopropyl) triethoxysilane (APTES) ldquobridgerdquo. Contact angle measurement and Auger electron spectroscopy (AES) was used to characterize steps of the process. L929 Cells were used to evaluate the biology effect of the modification. The results have shown that the chitosan modification could depress the adhesion of cells on silicon.

Using biomedical sensor - reflectometry interference spectroscopy for evaluation of biocompatibility of biomaterials

Using a biomedical sensor setup RIfS we have investigated the kinetic behavior of bovine serum albumin (BSA), human fibrinogen (FIb) and human IgG adsorbed onto surfaces of hydroxyapatite (HA) and polyurethane (PU) H50-50. According to the operation principle of RIfS and the molecular dimensions of three kinds of proteins, a formula to calculate the adsorbed layers of proteins onto the surface of HA and PU H50-50 has been introduced. The results show that the adsorbed layers of three kinds of proteins on the surface of HA are 1.0751 for IgG 0.9684 for BSA, 0.7464 for FIb and that of PU H50-50 are: 0.8199 for IgG 0.7964 for BSA, 0.6120 for FIb. It is shown that RIfS can perform a kinetic, real time and in situ analysis of plasma proteins adsorbed on a surface of biomaterials. From this study the potential application of RIfS as a new analytical tool in the evaluation of the biocompatibility of biomaterials was confirmed and the experiences of preparing suitable nanograde film from inorganic and organic biomaterials for a RIfS experiment were accumulated.

Implanted Electronic Siren to Alarm for Bladder Full with Urine

A Device to detect for the bladder which is full with urine is designed. The device can measure bladder pressure. The pressure signals are processed. When the pressure exceeds 40cm water column, Pressure signal exceeds a fixed voltage. At the same time, Oscillator sends a signal and the signal transmits to the body surface. The receiver accepts the oscillating signal. Then, the alarm alerts. Liquid pressure sensor is used to measure bladder pressure. Signal transmits through a pig bladder to pigskin to verify the feasibility of the program.