Galvanic Brain-Coupled Communication Among Freely Floating Micro-Scale Implants

This paper presents a new communication method between micro-scale freely floating brain implants based on galvanic coupling (GC), called "Brain-Coupled Communication" (BCC). Since the transmission efficiency based on GC is highly dependent on the system’s geometry and the electromagnetic properties of the tissue, finite element models in COMSOL...

Improving the Security of the IEEE 802.15.6 Standard for Medical BANs

A Medical Body Area Network (MBAN) is an ensemble of collaborating, potentially heterogeneous, medical devices located inside, on the surface of or around the human body with the objective of tackling one or multiple medical conditions of the MBAN host. These devices-which are a special category of Wireless Body Area Networks (WBANs)–collect,...

A Chip Integrity Monitor for Evaluating Moisture/Ion Ingress in mm-Sized Single-Chip Implants

For mm-sized implants incorporating silicon integrated circuits, ensuring lifetime operation of the chip within the corrosive environment of the body still remains a critical challenge. For the chip's packaging, various polymeric and thin ceramic coatings have been reported, demonstrating high biocompatibility and barrier properties. Yet, for...

Long-term encapsulation of platinum metallization using a HfO2 ALD - PDMS bilayer for non-hermetic active implants

In this work, we investigate the insulating performance of an atomic layer deposited (ALD) HfO2 - polymer bilayer for platinum (Pt) metallization. As test vehicles, Pt interdigitated comb structures (IDC) were designed and fabricated on SiO2/Si substrates. The IDCs were first coated with a 100 nm thin HfO2 ALD layer. A group of samples was...

Zero-Power Defense Done Right: Shielding IMDs from Battery-Depletion Attacks

The wireless capabilities of modern Implantable Medical Devices (IMDs) make them vulnerable to security attacks. One prominent attack, which has disastrous consequences for the patient’s wellbeing, is the battery Denial-of-Service attack whereby the IMD is occupied with continuous authentication requests from an adversary with the aim of...

Circuit Design Considerations for Power-Efficient and Safe Implantable Electrical Neurostimulators

This paper presents the main circuit design considerations for power-efficient and safe implantable electrical neurostimulators. Related to medical applications, low-frequency (LF) stimulation for generating new action potentials and kilohertz-frequency alternating current (KHFAC) for blocking unwanted neural activity are introduced,...

A Chip Integrity Monitor for Evaluating Long-term Encapsulation Performance Within Active Flexible Implants

One key obstacle in employing silicon integrated circuits in flexible implants is ensuring a long-term operation of the chip within the wet corrosive environment of the body. For this reason, throughout the years, various biocompatible insulating materials have been proposed, yet, evaluating their long-term encapsulation performance on...

Mixed-Signal IC With Pulse Width ModulationWireless Telemetry for Implantable CardiacPacemakers in 0.18-μm CMOS

A low-power mixed-signal IC for implantable pacemakers is presented. The proposed system features three independent intracardiac signal readout channels with pulse-width-modulated outputs. Also, the proposed system is capable of measuring the amplitude and phase of the bioimpedance with pulse-width-modulated outputs for use in rate adaptive...

Does a coupling capacitor enhance the charge balance during neural stimulation? An empirical study

Due to their DC-blocking characteristic, coupling capacitors are widely used to prevent potentially harmful charge buildup at the electrode–tissue interface. Although the capacitors can be an effective safety measure, it often seems overlooked that coupling capacitors actually introduce an offset voltage over the electrode–tissue interface as...