MEA Technology
MEAs are a widely used methodology to access information of in vivo or in vitro electrogenic cell networks. It is a non invasive (i.e. extracellular) technology that allows long-term monitoring of large neuronal cell assemblies to reveal fundamental properties (e.g. plasticity, memory) of networks. Commercially available MEA systems implement up to 256 electrodes and can therefore only access a small number of neurons within a network consisting of several tens of thousands of cells. Furthermore, inter-electrode separations are in the order of 150 µm and thus all those systems suffer from a substantial spatially undersampled network representation since typical neuronal cell sizes from vertebrates are in the order of ten micrometers. If we want to monitor the activity both down to the cellular level and over an entire network, higher spatial resolution is unavoidably required and will stringently lead us to our high-resolution MEA system.
source:Multichannelsystems
APS Technology
A high degree of integration can be achieved by using state-of-the-art CMOS processes. Electrodes are densely fabricated and the technology also allows concurrent implementation of required electronics within each electrode element. This concept originally stems from the technology of CMOS-based optical cameras, where the light sensitive elements are replaced with metallic electrodes. Our high-density MEAs featuring up to 4096 channels at an individual sampling frequency of 10 kHz produce a high-speed, multiplexed data stream. In real-world applications processing time can be a key requirement and therefore, we included several real-time processing blocks (FPGAs, DSPs) in the acquisition system.
Real-Time Technology
Conventional low-density MEA systems employ signal processing tasks, such as signal enhancement, spike detection and spike sorting, are usually performed in software on a host CPU. This approach is not practical for the processing of a high number of electrodes. Typically, our APS-MEA system that implements 4096 electrodes generates a data rate in the order of 500 Mbit/s. In order to simplify the acquisition system signal analysis tasks are implemented in hardware. We use Field Programmable Gate Arrays (FPGA) to program neurophysiological signal processing and analysis in hardware. Such a hardware-based approach enables real-time signal analysis for thousands of recording electrodes. Moreover, our system provides additional specific hardware resources (i.e. image processor) for the implementation of more flexible computational tasks.
