Publications de Reza Ranjandish

Walsh-Hadamard-Based Orthogonal Sampling Technique for Parallel Neural Recording Systems

Walsh-Hadamard based orthogonal sampling of signals is studied in this paper, and an application of this technique is presented. Using orthogonal sampling, a single analog-to-digital converter (ADC) only is sufficient to perform parallel (simultaneous) rec ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2021

A Review of Microelectronic Systems and Circuit Techniques for Electrical Neural Recording Aimed at Closed-Loop Epilepsy Control

Alexandre Schmid, Reza Ranjandish

Closed-loop implantable electronics offer a new trend in therapeutic systems aimed at controlling some neurological diseases such as epilepsy. Seizures are detected and electrical stimulation applied to the brain or groups of nerves. To this aim, the signa ...

2020

A design methodology for charge-balanced stimulators based on anodic current variation monitoring

Alexandre Schmid, Reza Ranjandish

Charge balancing is a major safety concern in neural and functional electrical stimulation. This paper presents a novel and safe active charge balancing design methodology in which, after each cathodic and anodic stimulation pulse, the value of the remaini ...

2019

Chopped-Anodic-Phase Charge Balancing Method for Electrical Stimulation

Alexandre Schmid, Reza Ranjandish

Providing safety of stimulation is a critical requirement in the design of biomedical electrical stimulators. Charge balancing circuits are required to guarantee safety of electrical stimulators. Chopped-anodic-phase (CAP) is one of the methods used for ch ...

IEEE2019

Implantable Autonomous Wireless Closed-loop Bio-electronics for Epilepsy Control

Reza Ranjandish

Implantable electronic medical device (IEMD) is an emerging technology that plays an important role in the treatment of several neurological disorders such as epilepsy, especially in the cases of drug-resistant epilepsy. Recent developments and studies sho ...

EPFL2019

A Fully Fail-Safe Capacitive-Based Charge Metering Method for Active Charge Balancing in Deep Brain Stimulation

Alexandre Schmid, Reza Ranjandish

Related to safety issues, charge balancing is a major concern in neural and functional electrical stimulation. This paper presents a capacitive-based charge metering method as a low-power and precise charge balancing method used in Deep Brain Stimulation ( ...

IEEE2018

An Active Charge Balancing Method Based on Chopped Anodic Phase

Alexandre Schmid, Reza Ranjandish

A new method for safe electrical neural stimulation is proposed. A negative feedback is used to automatically produce short anodic pulses according to the remaining voltage. The period of the short anodic pulses varies according to the remaining voltage. T ...

IEEE2018

All Wireless, 16-channel Epilepsy Control System with Sub-mu W/channel and Closed-loop Stimulation Using a Switched-Capacitor-Based Active Charge Balancing Method

Catherine Dehollain, Alexandre Schmid, Franco Maloberti, Kerim Türe, Reza Ranjandish

An all wireless closed-loop stimulation system for epilepsy control is presented that generates charged-balanced programmable stimulation current pulses upon a seizure is detected. The proposed system has highly flexible stimulation parameters thanks to th ...

IEEE2018

A 4-channel 5.04 μW 0.325 mm2 Orthogonal Sampling-Based Parallel Neural Recording System

Alexandre Schmid, Reza Ranjandish

The application of orthogonal sampling for parallel neural recording is presented in this paper. Orthogonal sampling enables reducing the number of the I Cs in conventional recording systems into one single unit. Consequently, the ADC bandwidth and dynamic ...

IEEE2018

Current Overshoots and Undershoots in Electrical Stimulation: A Circuit-level Perspective of the Origin and Solutions

Alexandre Schmid, Reza Ranjandish

This paper investigates a common phenomenon in current mode stimulation which is known as current overshoots and undershoots. The origin of these abnormalities in the current pulses has remained an open issue and these overshoots and undershoots have been ...

IEEE2018

A Sub-μW/Channel, 16-Channel Seizure Detection and Signal Acquisition SoC Based on Multichannel Compressive Sensing

Alexandre Schmid, Reza Ranjandish

An accurate 16-channel seizure detection system-on-chip is presented, which is based on extracting features from the compressed recorded data using multichannel compressive sensing (MCS). MCS is used to reduce the transmission data rate of sparse biologica ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2018

Implantable IoT System for Closed-Loop Epilepsy Control based on Electrical Neuromodulation

Alexandre Schmid, Reza Ranjandish

A closed-loop system aiming at epilepsy control is proposed in this paper, in which electrical stimulation is triggered upon a decision aggragating different biological signatures of the seizure such as changes in the heart rate, blood flow in the brain, a ...

IEEE2018

Power/data platform for high data rate in implanted neural monitoring system

Catherine Dehollain, Alexandre Schmid, Gürkan Yilmaz, Franco Maloberti, Kerim Türe, Reza Ranjandish

IEEE2017