Nv
N.F. van Lith
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1
VoNA The Visualisation of Neuronal Activation
To observe and shape electrode-generated outputs for electrical stimulation in the brain using a Finite Element Model
The development of neural prostheses, especially those directly targeting the brain, requires extensive research and modelling before clinical trials can be performed. Currently, the resolution of artificial vision is not sufficient for everyday tasks. By studying the expected spatial extent of stimulation, we aim to provide insights to researchers that can be used to improve the resolution of artificial vision. The goal of this MSc thesis was to visualise the shape and intensity of electric fields in the cortex as a response to intracortical microelectrode stimulation to observe the expected regions of neuronal activation considering electrode design parameters. To do this, parameters that can influence the generated electric field and the regions of activated tissue have been defined. Implementing these parameters in a Finite Element Model (FEM) allows the computation of the generated electric field in 3D of a stimulating electrode to observe the spatial extent of activated tissue. The spatial extent of activated tissue can be estimated using simplified methods such as the activating function (AF) or current density threshold. The result is a parameterised framework that creates a Visualisation of Neuronal Activation (VoNA) that can be used to assess activated tissue regions for varying scenarios by defining material properties and dimensions of the model, and allows for the adjustment of the stimulation configuration, electrode contact spacing, customisation of electrode size and modulation of stimulation current. It enables the user to tune the model settings towards their specific needs and explore the possibilities by visualising the results from different angles by defining subsets of the entire solution. In line with expectations, the presented models show that the model parameters can influence factors such as the generated electric field, the current density and electric potential, which are indicators of neuronal activation. The findings support the hypothesis that these parameters should be considered during electrode design to achieve accurate stimulation.
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The development of neural prostheses, especially those directly targeting the brain, requires extensive research and modelling before clinical trials can be performed. Currently, the resolution of artificial vision is not sufficient for everyday tasks. By studying the expected spatial extent of stimulation, we aim to provide insights to researchers that can be used to improve the resolution of artificial vision. The goal of this MSc thesis was to visualise the shape and intensity of electric fields in the cortex as a response to intracortical microelectrode stimulation to observe the expected regions of neuronal activation considering electrode design parameters. To do this, parameters that can influence the generated electric field and the regions of activated tissue have been defined. Implementing these parameters in a Finite Element Model (FEM) allows the computation of the generated electric field in 3D of a stimulating electrode to observe the spatial extent of activated tissue. The spatial extent of activated tissue can be estimated using simplified methods such as the activating function (AF) or current density threshold. The result is a parameterised framework that creates a Visualisation of Neuronal Activation (VoNA) that can be used to assess activated tissue regions for varying scenarios by defining material properties and dimensions of the model, and allows for the adjustment of the stimulation configuration, electrode contact spacing, customisation of electrode size and modulation of stimulation current. It enables the user to tune the model settings towards their specific needs and explore the possibilities by visualising the results from different angles by defining subsets of the entire solution. In line with expectations, the presented models show that the model parameters can influence factors such as the generated electric field, the current density and electric potential, which are indicators of neuronal activation. The findings support the hypothesis that these parameters should be considered during electrode design to achieve accurate stimulation.
Wired sensor network for measuring fat deposition in extraction channels
A Power Supply and Communication Module
Bachelor thesis
(2018)
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Niels van Lith, Swier Garst, Andre Bossche, Jeroen Bastemeijer, Nick van der Meijs, Stephan Wong
The goal of this project is to identify the most promising measurement method and strategy for measuring the thickness of grease and to design a sensor module with electronic read-out and communication module. This project has been split into two parts: a sensor implementation and a communication system. This report describes the design and implementation of the communication module and power supply. The communication module has been designed to work conform a master-slave principle using MODBUS over an RS-485 databus. The used hardware for the communication module is rated to work within a desired 1 to 100m range. Furthermore the master node is connected to the internet to present the data on a small webserver. The power supply design depends on the implementation of the sensor, and contains the use of linear voltage regulators and inverters. The results show that the communication module works properly, whereas the power supply requires some further work.
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The goal of this project is to identify the most promising measurement method and strategy for measuring the thickness of grease and to design a sensor module with electronic read-out and communication module. This project has been split into two parts: a sensor implementation and a communication system. This report describes the design and implementation of the communication module and power supply. The communication module has been designed to work conform a master-slave principle using MODBUS over an RS-485 databus. The used hardware for the communication module is rated to work within a desired 1 to 100m range. Furthermore the master node is connected to the internet to present the data on a small webserver. The power supply design depends on the implementation of the sensor, and contains the use of linear voltage regulators and inverters. The results show that the communication module works properly, whereas the power supply requires some further work.