A micro-electromechanical fluid ejection device includes a substrate. The methods include culturing neuronal cells with microparticles to provide a microparticle and neuronal cell culture composition, wherein the microparticles are coated with a compound that provides for attachment of neuronal cells. Each node object can corresponds to a node, which corresponds to at least one process flow. The ADC subcircuits operate in current mode rather than voltage mode in order to further accelerate their operations and provide lower cost.