Xicai Yue

A Real-Time Multi-Channel Monitoring System for Stem Cell Culture Process

A novel, up to 128 channels, multi-parametric physiological measurement system suitable for monitoring hematopoietic stem cell culture processes and cell cultures in general is presented in this paper. The system aims to measure in real-time the most important physical and chemical culture parameters of hematopoietic stem cells, including physicochemical parameters, nutrients, and metabolites, in a long-term culture process. The overarching scope of this research effort is to control and optimize the whole bioprocess by means of the acquisition of real-time quantitative physiological information from the culture. The system is designed in a modular manner. Each hardware module can operate as an independent gain programmable, level shift adjustable, 16 channel data acquisition system specific to a sensor type. Up to eight such data acquisition modules can be combined and connected to the host PC to realize the whole system hardware. The control of data acquisition and the subsequent management of data is performed by the systems software which is coded in LabVIEW. Preliminary experimental results presented here show that the system not only has the ability to interface to various types of sensors allowing the monitoring of different types of culture parameters. Moreover, it can capture dynamic variations of culture parameters by means of real-time multi-channel measurements thus providing additional information on both temporal and spatial profiles of these parameters within a bioreactor. The system is by no means constrained in the hematopoietic stem cell culture field only. It is suitable for cell growth monitoring applications in general.

Biocompatible ion selective electrode for monitoring metabolic activity during the growth and cultivation of human cells.

Ammonia is the main nitrogenous waste product of cellular metabolism and if accumulated in culture media may limit cell growth and affect the quality of cultured cell lines. Therefore, it is crucial to control levels of this metabolite during the in vitro expansion of human cells. This paper describes the successful application of ion selective electrodes (ISE) to continuously monitor ammonium concentrations in a perfused cell bioreactor. The polymeric membranes of the ISE were cast from carboxylated poly(vinyl chloride) (PVC-COOH) and doped with highly hydrophilic poly(ethylene glycol) (PEG). The PEG was incorporated into the surface of the sensors in order to reduce the effect of biofouling without impairing their analytical characteristics. The electrodes developed enabled fast and selective measurements of ammonia in the range 0.5-5mM, corresponding well with the concentration determined off-line. Additionally, the UV sterilised sensors were small and flexible enough to be readily inserted into the limited space of the bioreactor. Long-term analytical performance of PEG-modified ISE during continuous measurements in mammalian cell cultures was investigated. The sensors remained stable for the duration of the bioprocess, 7 days.

A Low-Power Low-Distortion Amplifier for Fly Neural Recordings

This paper presents the design and simulation of a low-power and low-distortion amplifier for fly neural recordings based on a gain boosted differential operational-transconductance amplifier (OTA). The amplifier has been designed in a commercially available 0.35µm CMOS process. Powered by 1.5V, it consumes 16.5µW and has a gain of 66+dBs and a bandwidth of 10 KHz. Its gain and linearity are not sensitive to power supply variations, making it suitable for feeding by a paper battery when recording brain neural signals from moving flies. The designed amplifier is capable of driving a 10pF capacitive load therefore it can be directly connected to an oscilloscope or an ADC input.

8×16 channel physiological monitoring platform of stem cell culture systems

An up to 128 channel PC-based physiological measurement platform for stem cell cultures is presented in this paper. The platform is designed to measure the most important stem cell culture parameters namely pH, temperature and glucose in real-time. The aim is to optimize the whole bioprocess by means of the acquisition of real-time, on-line, in-situ quantitative physiology information from the culture. The hardware system of the physiological measurement platform is designed in a modular manner. Each is designed as an independent 16 channel data acquisition system specific to a sensor type. Up to eight data acquisition modules are connected together and then connected to the host PC to form the 8times16 channel physiological measurement platform. The host PC is mainly used for data acquisition process control. With the virtual instrumentation application software programmed in LabVIEW, the user-friendly interface of physiological measurement platform is easy to use in facilitating the acquisition, display and management different types of physiological data. The platform is generic by design and can be interfaced with a variety of potentiometric and amperometric sensors. This operational attributes renders the platform suitable for any cell culture application where quality control is needed through the quantitative monitoring of the bioprocess and its subsequent informed assessment and interpretation. Furthermore, the modular structure facilitates the introduction of new sensor to the platform.