Provided herein are high-input detector modules and multi-input biological classifier circuits and systems that integrate sophisticated sensing, information processing, and actuation in living cells and permit new directions in basic biology, biotechnology and medicine. The multi-input biological classifier circuits described herein comprise synthetic, scaleable transcriptional/post-transcriptional regulatory circuits that are designed to interrogate the status of a cell by simultaneously sensing expression levels of multiple endogenous inputs, such as microRNAs. The classifier circuits then compute whether to trigger a desired output or response if the expression levels match a pre-determined profile of interest.