Advances in large-scale electrophysiology with high-density microelectrode arrays.

A detailed functional characterization of electrogenic cells, such as neurons and cardiomyocytes, by means of high-density microelectrode arrays (HD-MEAs) has emerged as a powerful approach for inferring cellular phenotypes and elucidating fundamental mechanisms underlying cellular function. HD-MEAs have been applied across a range of disciplines, including neurodevelopmental research, stem cell biology, and pharmacology, and more recently in interdisciplinary work at the intersection of biomedical engineering, computer science, and artificial intelligence (AI). Innovations in chip design, fabrication, recording capabilities, and data processing have significantly advanced the functionality of HD-MEAs.

A Low-Cost Multimodal Testbed for Array-Based Electrophysiological Microelectrodes.

Electrode designs and materials have become an increasingly important performance driver for microelectrode arrays, which are among the essential tools for cellular electrophysiology. Ongoing works have continuously innovated over a diverse range of electrode shapes, sizes, and materials. The large design and fabrication parameter space represents rich opportunities for optimizing performance and functionalities as well as a challenge for electrode developers due to a lack of predictive simulation software to aid design works.

Microfluidic Platform for Real-Time Impedance Profiling of Transwell-Based Barrier Models.

We propose a microfluidic platform with integrated microfabricated electrodes for real-time impedance profiling of transwell-based barrier models, which can be subjected to dynamic microfluidic flow. This platform overcomes the limitations of conventional methods that are based on invasive permeability assays and single time-point impedance measurements: It enables continuous, non-invasive monitoring of tissue barrier integrity at high spatial and temporal resolution. We demonstrate the capabilities of our system by continuously monitoring the gradual loss of barrier integrity in upper-airway-tissue models exposed to non-physiological liquid-liquid interface conditions.

Seamless integration of CMOS microsensors into open microfluidic systems.

As traditional two-dimensional (2D) cell cultures offer limited predictive capabilities for drug development, three-dimensional (3D) tissue models, such as spherical microtissues, have been introduced to better reproduce physiological conditions. The hanging-drop method, used to cultivate microtissues at an air-liquid interface, proves to be effective for microtissue formation and maintenance. Using that technology, it is possible to fluidically interconnect several hanging drops hosting different models of human organs to recapitulate relevant tissue interactions.

A 4096 channel event-based multielectrode array with asynchronous outputs compatible with neuromorphic processors.

Bio-signal sensing is pivotal in medical bioelectronics. Traditional methods focus on high sampling rates, leading to large amounts of irrelevant data and high energy consumption. We introduce a self-clocked microelectrode array (MEA) that digitizes bio-signals at the pixel level by encoding changes as asynchronous digital address-events only when they exceed a threshold, significantly reducing off-chip data transmission.

A Time-Domain Readout Technique for Neural Interfaces Based on VCO-Timestamping.

CMOS neural interfaces are aimed at studying the electrical activity of neurons and may help to restore lost functions of the nervous system in the future. The central function of most neural interfaces is the detection of extracellular electrical potentials by means of numerous microelectrodes positioned in close vicinity to the neurons. Modern neural interfaces require compact low-power, low-noise readout circuits, capable of recording from thousands of electrodes simultaneously without excessive area consumption and heat dissipation.

3D In Vitro Blood-Brain-Barrier Model for Investigating Barrier Insults.

Blood-brain-barrier (BBB) disruption has been associated with a variety of central-nervous-system diseases. In vitro BBB models enable to investigate how the barrier reacts to external injury events, commonly referred to as insults. Here, a human-cell-based BBB platform with integrated, transparent electrodes to monitor barrier tightness in real time at high resolution is presented.

Circuit-Based Design of Microfluidic Drop Networks.

Microfluidic-drop networks consist of several stable drops-interconnected through microfluidic channels-in which organ models can be cultured long-term. Drop networks feature a versatile configuration and an air-liquid interface (ALI). This ALI provides ample oxygenation, rapid liquid turnover, passive degassing, and liquid-phase stability through capillary pressure.

Impedance Imaging of Cells and Tissues: Design and Applications.

Due to their label-free and noninvasive nature, impedance measurements have attracted increasing interest in biological research. Advances in microfabrication and integrated-circuit technology have opened a route to using large-scale microelectrode arrays for real-time, high-spatiotemporal-resolution impedance measurements of biological samples. In this review, we discuss different methods and applications of measuring impedance for cell and tissue analysis with a focus on impedance imaging with microelectrode arrays in applications.

A Low-Power Opamp-Less Second-Order Delta-Sigma Modulator for Bioelectrical Signals in 0.18 µm CMOS.

This article reports on a compact and low-power CMOS readout circuit for bioelectrical signals based on a second-order delta-sigma modulator. The converter uses a voltage-controlled, oscillator-based quantizer, achieving second-order noise shaping with a single opamp-less integrator and minimal analog circuitry. A prototype has been implemented using 0.

A VCO-Based CMOS Readout Circuit for Capacitive MEMS Microphones.

Microelectromechanical systems (MEMS) microphone sensors have significantly improved in the past years, while the readout electronic is mainly implemented using switched-capacitor technology. The development of new battery powered "always-on" applications increasingly requires a low power consumption. In this paper, we show a new readout circuit approach which is based on a mostly digital Sigma Delta ( Σ Δ ) analog-to-digital converter (ADC).

SNDR Limits of Oscillator-Based Sensor Readout Circuits.

This paper analyzes the influence of phase noise and distortion on the performance of oscillator-based sensor data acquisition systems. Circuit noise inherent to the oscillator circuit manifests as phase noise and limits the SNR. Moreover, oscillator nonlinearity generates distortion for large input signals.