High-Density Integrated Electrocortical Neural Interfaces: Low-Noise Low-Power System-on-Chip Design Methodology

Description

High-Density Integrated Electrocortical Neural Interfaces provides a basic understanding, design strategies and implementation applications for electrocortical neural interfaces with a focus on integrated circuit design technologies. A wide variety of topics associated with the design and application of electrocortical neural implants are covered in this book. Written by leading experts in the field-Dr. Sohmyung Ha and Dr. Gert Cauwenberghs-the book discusses basic principles and practical design strategies of electrocorticography, electrode interfaces, signal acquisition, power delivery, data communication, and stimulation. In addition, an overview and critical review of the state-of-the-art research is included. These methodologies present a path towards the development of minimally invasive brain-computer interfaces capable of resolving microscale neural activity with wide-ranging coverage across the cortical surface. Contents About the authors Preface Acknowledgment 1 Introduction to ECoG interfaces 1.1 Introduction 1.2 Electrocorticogram 1.3 Volume conduction with differential electrodes 1.3.1 Differential recording 1.3.2 Differential stimulation 1.3.3 Electrode array configurations 1.4 Electrode interfaces for ECoG 1.5 ECoG interfaces: recording and stimulation 1.5.1 Integrated circuit interfaces for data acquisition 1.5.2 Integrated circuit interfaces for stimulation 1.5.3 Integrated electrocortical online data processing 1.6 System considerations 1.6.1 Powering 1.6.2 Wireless data communication 1.6.3 Hermetic encapsulation 1.7 Conclusion References 2 Integrated circuit interfaces for ECoG signal recording 2.1 Introduction 2.2 Requirements for ECoG signal recording 2.2.1 Physiological requirements 2.2.2 Design factors, inter-relations, and trade-offs 2.3 Subthreshold operation of MOS transistors 2.4 Basic architectures of instrumentation amplifiers 2.5 Basic amplifier design techniques 2.5.1 Noise-power trade-off 2.5.2 The gm/ID design methodology 2.5.3 Stability 2.6 Advanced techniques for instrumentation amplifier design 2.6.1 Offset and 1/f noise cancellation techniques 2.6.2 Pseudoresistors for sub-Hz highpass cutoff 2.6.3 CMRR enhancement techniques 2.6.3.1 Driven-right-leg technique 2.6.3.2 Input impedance boosting techniques 2.7 Conclusions References 3 ECoG signal coding and digitization 3.1 Introduction 3.2 Widely-used ADC architectures 3.2.1 Successive-approximation ADC 3.2.2 ΔΣ oversampling ADC 3.3 ADC-direct frontend 3.4 Circuit design implementation 3.5 Measurements 3.6 Conclusions References 4 Integrated circuit interfaces for electrocortical stimulation 4.1 Introduction 4.2 Electrical stimulation methodologies 4.2.1 Constant-voltage stimulation 4.2.2 Constant-current stimulation 4.2.3 Constant-current adiabatic stimulation 4.3 Design details of the stimulator 4.3.1 Overall architecture 4.3.2 Stimulation principle 4.3.3 Current controller 4.3.4 Adiabatic supply voltage generator 4.4 Experimental validation 4.5 Benchmarking stimulators 4.6 Conclusions References 5 Power management for mm-sized ECoG implants 5.1 Introduction 5.2 Architectural considerations 5.2.1 Importance of voltage and power conversion efficiency 5.2.2 Limitations of conventional cascaded rectification and regulation 5.3 Integrated resonant rectification and regulation 5.3.1 Benefits of integration 5.3.2 Hybrid pulse modulation 5.4 Circuit implementation 5.4.1 Event-driven variable pulse-width generator 5.4.2 Pulse-frequency modulation (PFM) control module 5.4.3 Pulse-width modulation (PWM) control module 5.5 Hybrid pulse modulation under RF input variation 5.6 Measurement results 5.7 Conclusions Acknowledgment References 6 RF power transmission and its considerations for ECoG implants 6.1 Introduction 6.2 Wireless power transmission modalities for miniaturized implants 6.2.1 Ultrasonic wireless power transmission 6.2.2 Electromagnetic wireless power transmission 6.3 Design considerations for fully integrated inductive wireless power receivers 6.3.1 RX coil design 6.3.2 Power and signal distribution 6.3.3 Impedance matching 6.4 Rectification and regulation 6.5 Adaptive buck-boost mode regulating rectifier 6.5.1 Mode arbiter 6.5.2 Feedback 6.5.3 Buck-mode RR 6.5.4 Boost-mode RR 6.6 Measurement results 6.7 Conclusions References 7 Wireless data communication for ECoG implants 7.1 Challenges of ECoG implants in wireless data communication 7.2 General approaches 7.3 COOK modulation scheme 7.3.1 Operation principle 7.3.2 Dependence on primary and secondary quality factors 7.3.3 Symbol data encoding 7.3.4 Resonance recovery and data rate 7.4 System implementation 7.5 Measurement results 7.6 Conclusion 7.7 Appendix References 8 Fully integrated modular ECoG recording and stimulation 8.1 State-of-the-art ECoG interface systems 8.2 Encapsulated neural interfacing acquisition chip (ENIAC) 8.3 Power and communication 8.4 Signal recording and stimulation 8.4.1 Recording 8.4.2 Stimulation 8.5 Conclusions References Index