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 105, a -3 dB bandwidth of 30 kHz, and an equivalent input noise of about 9 nV/(开方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 kΩ. They are intended to connect with both cuff-type and stag-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.

This paper presents a fully integrated and low power CMOS amplifier for neural signal recording. It consists of a band-filtering preamp and a current-mode instrumentation amplifier. The design approach and the noise optimizing are briefly discussed. A 0.6

The aim of present work was to study the interaction between human plasma protein-albumin (Alb) and immunoglobulin G (IgG) and the surfaces of two kinds of diamond-like Carbon (DLC-A and DLC-B) and titanium (Ti) film. Fourier transform infrared spectroscopy (FTIR) was used to perform both quantity investigation and secondary structure analysis of above two proteins adsorbed on material surfaces. A modified Coomassie brilliant blue (CBB) protein assay was also used to study the amount of adsorbed proteins. The result of FTIR quantitative evaluation shows that the ratio of adsorbed Alb to IgG (RA/I) on three kinds of material surface has an order: DLC-A > DLC-B > Ti, which is coincide with the result from CBB protein assay. The result of secondary structure analysis shows that the conformation of Alb and IgG changes in a largest degree after adsorbed on Ti and a smallest degree on DLC-A surface. Both the results indicate that the anti-thrombogenicity of DLC-A seems to be the best and Ti is the worst.

To prepare natural nano-HA and a natural nano-hydroxypatite/chitosan (CH) composite and to study the biocompatibility of natural nano-hydroxypatite/chitosan composite. Natural hydroxyapatite (HA) was prepared from animal’s bone according to a calcining method, the natural nano-HA was prepared by using planetary ball milling, and the composite was prepared via in-situ precipitation. TEM and SEM were used to observe the size of natural nao-hydroxypatite and the microstructure of the composite. The biocompatibility of natural nano-HA/CH composite was evaluated by MTT test. The TEM micrography of the natural nano-HA showed that the size of the particles is below 100nm, and the composite reported in this study has layer-by-layer structure. The result of MTT-test showed the cytotoxicity level of the prepared composite was 0. The nano-HA/CH composite has good biocompatibility, and it can be potentially applied as internal fixation of bone fracture.

An effective method for the quantitative evaluation of proteins adsorbed on biomaterial surfaces has been developed. First, the kinetic behavior of a range of human fibrinogen (Fib) adsorbed onto polystyrene (PS) films was investigated by using a reflectometry interference spectroscopy setup. The specific molecular number of adsorbed proteins, Np, was then defined. According to the definition, the numbers of Fib molecules adsorbed on PS films were calculated. An atomic force microscope (AFM) was used to scan the lateral distribution of the Fib molecules adsorbed on the PS films. From the AFM images, the practical specific molecular numbers were obtained by direct counting of the molecules. In order that the adsorbed number of Fib molecules on a unit area of the PS films could be counted easily, the solution concentration of proteins was reduced to 5ag/mL (10－18g/mL). There was good consistency between the numbers calculated with the formula defined by us and the numbers counted from AFM images. Therefore, the results of the present study prove the validity of our definition of the specific molecular number of adsorbed proteins and the effectiveness of the reflectometry interference spectroscopy-based method for quantitative evaluation of adsorptive proteins.