Hardware design

We present there a system-level overview of our recording hardware.

Hosting MEA-chips and PCB interfaces on-borad, the fully customized recording platform provide a complete signal chain, from the neural substrates to data acquisition terminal and downstream processing. The platform mainly consists of two layers of laser-cut acrylic board that are connected by a plastic hinge and can be locked in-place through a latch. This design eases loading and unloading of the chips and allows for rapid changes in recording configurations. Underneath the bottom layer, four soft rubber bumpers are affixed to insulate the platform against vibrations, minimizing recording noise. Secured to the top acrylic layer, a PCB provides the signal interface between the MEA chip and the Open Ephys data acquisition terminal. To ensure a firm, yet compliant contact with the MEA, arrays of spring-loaded contact (pogo) pins are soldered to the bottom of the PCB.

Upon loading a chip, the top layer is closed and locked with the pins gently making contact with metal pads patterned on the perimeter of the MEA. These pads, and the electronic tracks emanating from them, are designed to connect one-to-one with micro-electrodes located at the center of the chip, where neural substrates are plated and incubated. Signals sampled at each electrode are then transferred through these tracks, pogo pins and PCB before being received and processed by amplifier headstages located on the rear edge of the PCB. Intan Technologies headstages, connected to Open Ephys terminals through serial peripheral interface (SPI) cables, are utilized here because of their wide compatibility.

The platform is also designed with versatility that supports a range of recording capacities and configurations. Being compatible with a series of swappable PCB options, the platform can be configured with different recording capacities of 59, 128, 256 and 512 channels. Moreover, a series of add-on modules such as electrical and optical stimulators, fluidic interfaces and temperature sensors can be seamlessly integrated with the system for multimodal neuron stimulation and media refreshment. Made of fully customizable design and inexpensive materials, the hardware configuration is also easily reconfigurable to comply with industrial standard dimensions, such as the SBS 96-well micro-plate. This allows our system to be deployed inside common microscopic chambers, enabling concurrent imaging and electrophysiology recording.