Simultaneous stimulation and recording of retinal nerve cells with penetrating three dimensional multi-electrode arrays (MEA) on a localized area is a demanding challenge in next generation retina implant research. Within the scope of this research we developed a device to stimulate a network of bi-polar cells and record retinal ganglion cells with a slight time gap to overcome long recording dead times and switching artifacts in common stimulation-and recording systems. The device contains a four channel stimulator capable of pushing arbitrary bi-polar charges into the tissue and a 16 channel commercial electrophysiology interface chip. The device is a miniaturized front-end for our former developed embedded wireless communicating sensor node. First tests in in-vitro retina slices on adult rat with our device show reliable recordings of ganglia cell activity below 1ms after the bi-polar cell stimulation. Index Terms-functional electrical stimulation, neuronal recording, retina implant, embedded system
To understand the neural processes within retina cell layers recent retina implant research focusses on bidirectional communication with bi-polar and ganglion cells in in-vitro retinal tissue. In order to enable this research we had developed a front-end to stimulate and record retinal cell layers with a slight time gap only and thus avoiding long recording dead times. To ease experiments with this front-end, we developed a versatile and user optimized embedded data acquisition device, named iNODE5. This can be configured using a LabVIEW based graphical user interface. We adapted the front-end to the form factor of the commercial measurement device USB-6009OEM from National Instruments. Now, for evaluation and parameter testing the front-end can be plugged into the National Instruments board and controlled via a graphical user interface which enables the export of the basic configuration parameters for later automated standalone measurement and stimulation. For this the front-end is attached to the iNODE5 which reads the experiment configuration from the personal computer via USB or SD-card. The automated electrical stimulation and recording can be started or stopped by a terminal program or a button placed on the iNODE5.
In the fields of neurological rehabilitation and neurophysiological research there is a strong need for miniaturized, multi channel, battery driven, wireless networking DAQ systems enabling real-time digital signal processing and feedback experiments. For the scientific investigation on the passive auditory based 3D-orientation of Barn Owls and the scientific research on vegetative locomotor coordination of Parkinson's disease patients during rehabilitation we developed our 'intelligent Sensor and Actuator Network for Life science Application' (iSANLA) system. Implemented on the ultra low power microcontroller MSP430 sample rates up to 96 kHz have been realised for single channel DAQ. The system includes lossless local data storage up to 4 GB. With its outer dimensions of 20mm per rim and less than 15 g of weight including the Lithium-Ion battery our modular designed sensor node is thoroughly capable of up to eight channel recordings with 8 kHz sample rate each and provides sufficient computational power for digital signal processing ready to start our first mobile experiments. For wireless mobility a compact communication protocol based on the IEEE 802.15.4 wireless standard with net data rates up to 141 kbit/s has been implemented. To merge the lossless acquired data of the distributed iNODEs a time synchronization protocol has been developed preserving causality. Hence the necessary time synchronous start of the data acquisition inside a network of multiple sensors with a precision better than the highest sample rate has been realized.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.