Design and fabrication of MEMS based intracranial pressure sensor for neurons study

Abstract

Neural sensing has been the backbone of neuroscience research, brain-machine interfaces and clinical neuromodulation therapies for decades. To date, most of the neural stimulation systems have relied on sharp thin film electrodes with poor electrical properties that cause extensive damage to the tissue and significantly degrade the long-term stability of implantable systems. So, here in view of a safer course of action and better results, a flexible microelectrode array is proposed, which is capable of sensing neural stimulation from the neuron surface, without penetrating the tissue. A multi electrode array (MEA) is a micro-fabricated cell culture dish with embedded microelectrodes at the bottom of the dish. The size of the sensor is decided by the size of the sensor chip and package. The sensor chip is based on silicon wafer ,which is piezo resistive effect and the size is 100 × 200 μm2. It is much smaller than the reported polymer intracranial pressure sensors such as liquid crystal polymer sensors. Recently MEAs with different cell-adhesive patterns are actively used to analyse the behaviours under study in vitro neural systems. The MEAs also integrate with pressure sensor and temperature sensor. So the MEAs confirm the synaptic connection of the in vitro neuron stimulation, and a passive piezo resistive resonant sensor that accurately monitors intracranial pressures based on the Wheatstone bridge. Also it shows the present temperature condition of culture dish. As the device is fabricated using MEMS technology with biocompatible material, it has been shown to be non-irritating to cells even if it works for long term measurement. The sensitivity of the sensor is 0.84 × 10−2 mV/kPa and the minimum level of pressure is acquired in the range of 112 Pa in average. From the MEA, temperature and pressure data, the neurological disorder is identified.