Design and implementation of a multi-modal sensor with on-chip security

With the advancement of technology, wearable devices for fitness tracking, patient monitoring, diagnosis, and disease prevention are finding ways to be woven into modern world reality. CMOS sensors are known to be compact, with low power consumption, making them an inseparable part of wireless medical applications and Internet of Things (IoT). Digital/semi-digital output, by the translation of transmitting data into the frequency domain, takes advantages of both the analog and digital world. However, one of the most critical measures of communication, security, is ignored and not considered for fabrication of an integrated chip. With the advancement of Moore\u27s law and the possibility of having a higher number of transistors and more complex circuits, the feasibility of having on-chip security measures is drawing more attention. One of the fundamental means of secure communication is real-time encryption. Encryption/ciphering occurs when we encode a signal or data, and prevents unauthorized parties from reading or understanding this information. Encryption is the process of transmitting sensitive data securely and with privacy. This measure of security is essential since in biomedical devices, the attacker/hacker can endanger users of IoT or wearable sensors (e.g. attacks at implanted biosensors can cause fatal harm to the user). This work develops 1) A low power and compact multi-modal sensor that can measure temperature and impedance with a quasi-digital output and 2) a low power on-chip signal cipher for real-time data transfer

A novel Three-Dimensional Micro-Electrode Array for in-vitro electrophysiological applications

Microelectrode arrays (MEAs) represent a powerful and popular tool to study in vitro neuronal networks and acute brain slices. The research standard for MEAs is planar or 2D-MEAs, which have been in existence for over 30 years and used for extracellular recording and stimulation from cultured neuronal cells and tissue slices. However, planar MEAs suffer from rapid data attenuation in the z-direction when stimulating/recording from 3D in-vitro neuronal cultures or brain slices. The existing proposed 3D in-vitro neuronal models allow to record the electrophysiological activity of the 3D network only from the bottom layer (i.e. the one directly coupled to the planar MEAs). Thus, to further develop and optimize such 3D neuronal network systems and to study and understand how the 3D neuronal network dynamics changes in different layers of the 3D structure, new three-dimensional microelectrodes arrays (3D-MEAs) are required. Early attempts in this field resulted in interesting integrated approaches toward protruding or spiked 3D-MEAs. Although these first prototypes could be successfully employed with brain slices, the limited heights of the electrodes (up to max 70 \u3bcm) and the peculiar shape of the recording areas made them not an ideal solution for 3D neuronal cultures. Moreover, a convenient and versatile method for the fabrication of multilevel 3D microelectrode arrays has yet to be obtained, due to the usually complicated and expensive designs and a lack of a full compatibility with standard MEAs both in terms of materials and recording area dimensions. To overcome the afore-mentioned challenges, in this work, I present the design, microfabrication, and characterization of a new 3D-MEA composed of pillar-shaped gold 3D structures with heights of more than 100 \u3bcm that can be used, in principle, on every kind of MEA, both custom-made and commercial. I successfully demonstrate the capability and ability of such 3D-MEA to record electrophysiological spontaneous activity from 3D engineered in-vitro neuronal networks and both 4-AP-induced epileptiform-like and electrically-evoked activity from mouse acute brain slices. I also demonstrate how the developed 3D-MEA allows better recording and stimulating conditions while interfacing with acute brain slices as compared to planar electrode arrays and previously reported 3D MEA technologies