Conventional microelectrode arrays, also known as multielectrode arrays (MEAs), allow the user to simultaneously record from a very small number of neurons, limiting the recorded data to only a fraction of the active neurons within the neural network. At 3Brain, we have worked for many years to introduce CMOS-APS technology to the field of electrophysiology and functional imaging. CMOS-APS technology overcomes the limitations of conventional microelectrode arrays, or multielectrode arrays, by drastically increasing the number of simultaneously recording electrodes—up to several thousands.
CMOS-technology is used to build cost-efficient systems such as microprocessors, wireless receivers, GPS and cameras. We pushed the MEA technology to new dimensions by using the concept of active-pixel-sensor technology (APS) employed in the world of imaging devices and cameras. Instead of light-sensitive elements used for camera chips, we integrate a metallic electrode into each unit element, called a pixel. The pixel has the shape of a square with the size of a few tens of micrometers.
A large number of these squares are placed in a matrix of microelectrodes to build a microelectrode array, or multielectrode array, culminating in a new disruptive method of gathering high-resolution data orders of magnitude higher than what can be obtained with conventional microelectrode arrays, or multielectrode arrays.
Each pixel integrates amplification and filter stages directly where the biological signals are measured. Consequently, the signal from each microelectrode can already be processed and enhanced at a local level. Unlike conventional MEA technology, our CMOS-MEA can output the signals from many electrodes to a single wire. Thus, we reduce the need for many interconnection lines and have reduced the size of the signal-processing blocks. In addition, this approach is highly scalable with respect to the number of electrodes and interconnections, which do not have to scale accordingly.