Microorganisms account for most of the biodiversity on earth. Yet while there are increasingly powerful tools for studying microbial genetic diversity, there are fewer tools for studying microorganisms in their natural environments. In this paper we will summarize recent advances in CMOS electrochemical imaging for detecting and classifying microorganisms, and present new experimental recordings of single algae cells using an electrochemical impedance spectroscopy (EIS) sensor array. Integrated electrochemical microbial sensing has the potential to lead to improved medical diagnostics and environmental monitoring, as well as discoveries of new microbial populations.