Development of Mini Space Bioreactor System

微重力对空间细胞培养的影响规律一直是国际空间生物学的重点研究领域。而空间细胞培养技术和方法作为空间细胞生物学研究的基础，其概念性和原理性设计是正确区分重力对细胞的直接作用和间接作用的前提。另外，空间实验成本高昂，空间细胞培养装置的体积、重量、功耗是首要的制约因素。为保证充分物质交换，满足细胞代谢需求，同时尽可能降低由细胞供液形式产生的力学环境对细胞的影响，区分重力对细胞的直接作用和间接作用，我们研制了逆流片层式微型细胞培养装置。实验表明为使培养液流动对细胞生长影响最小，流动剪切应变率应小于1s-1。通过理论计算分析的逆流片层式微型细胞培养装培养室内流场及流动剪切范围表明，该装置可以满足要求。通过实验检测细胞培养时的氧耗、糖耗等，可以确定不同种类细胞的培养液流量范围。培养室内采用经表面改性的聚合物网架作为细胞载体，使得培养空间得到充分利用，并利于操作。从而为空间细胞培养研究提供了一种新的技术手段。

A mini-staged multi-stacked quantum cascade laser for improved optical and thermal performance

In this paper, a mini-staged multi-stacked quantum cascade laser structure with a designed wavelength of 4.7 mu m is presented. By introducing five 0.5 mu m thick high thermal conductivity InP interbuffer layers, the 60-stages active region core of the quantum cascade laser is divided into six equal parts. Based on simulation, this kind of quantum cascade laser with a 10 mu m ridge width gives nearly circular two-dimensional far-field distribution (FWHM = 32.8 degrees x 29 degrees) and good beam quality parameters M-2 = 1.32 x 1.31 in the fast axis (growth direction) and the slow axis (lateral direction). Due to the enhancement of lateral heat extraction through the interbuffer layers, compared to the conventional structure, a decrease of about 5-6% for the maximum temperature in the active region core of the mini-staged multi-stacked quantum cascade laser with indium-surrounded and gold-electroplated packaging profiles is obtained at all possible dissipated electrical power levels.

Neuro-Stimulus Chip with Photodiodes Array for Sub-retinal Implants

A prototype neuro-stimulus chip for sub-retinal implants in blind patients affected by Age-related Macular Degeneration (AMD) or Retinitis Pigmentosa (RP) is presented in this paper. This retinal prosthetic chip was designed to replace the degenerated photoreceptor cells, and in order to stimulate directly the remaining healthy layers of retinal neurons. The current stimulus circuits are monolithic integrated with photodiodes (PD) array, which can convert the illumination on the eyes into bi-phasic electrical pulses. In addition, a novel charge cancellation circuit is used to discharge the electrodes for medical safty. The prototype chip is designed and fabricated in HJTC 0.18 mu m N-well CMOS 1P6M Mix-signal process, with a +/- 2.5 V dual voltage power supply.

Electrochemiluminescent microoptoprobe with mini-grid working electrode and self-contained sample container

A new electrochemiluminescence (ECL) microoptoprobe with simple structure. small sampling volume and high efficiency was developed. It was constructed by fixing the transparent gold mini-grid on the end surface of the optical fiber, and by surrounding the fiber with the counter- and reference electrodes to form a self-contained three-electrode system. The use of mini-grid electrode increased the surface area and collection efficiency. which resulted in higher ECL signal and better sensitivity. The counter electrode together with one end of the fiber formed a mini-vessel, which eliminated the need of additional container and allowed to perform ECL detection in a very small volume (about 10 mul). The microoptoprobe obtained was characterized with the Ru(bpy)(3)(2-)-tripropylamine system and was applied for the determination of oxalate and chlorpromazine (CPZ). Detection limits (S/N = 3) were 5 x 10(-7) and 1 x 10(-6) mol l(-1) for oxalate and CPZ. respectively. The linear range for oxalate and CPZ extended from 1 x 10(-6) to 1 x 10(-3) mol l(-1), and from 5 x 10(-6) to 5 x 10(-4) mol l(-1). respectively.

Mini-electrochemical detector for microchip electrophoresis

This paper presents the development of a mini-electrochemical detector for microchip electrophoresis. The small size (3.6 x 5.0 cm(2), W x L) of the detector is compatible with the dimension of the microchip. The use of universal serial bus (USB) ports facilitates installation and use of the detector, miniaturizes the detector, and makes it ideal for lab-on-a-chip applications. A fixed 10 M Omega feedback resistance was chosen to convert current of the working electrode to voltage with second gain of 1, 2, 4, 8, 16, 32, 64 and 128 for small signal detection instead of adopting selectable feedback resistance. Special attention has been paid to the power support circuitry and printed circuit board (PCB) design in order to obtain good performance in such a miniature size. The working electrode potential could be varied over a range of +/-2.5 V with a resolution of 0.01 mV. The detection current ranges from -0.3 x 10(-7) A to 2.5 x 10(-7) A and the noise is lower than 1 pA. The analytical performance of the new system was demonstrated by the detection of epinephrine using an integrated PDMS/glass microchip with detection limit of 2.1 mu M (S/N = 3).