Vitamin C (ascorbate) deficiency is a global public health issue most prevalent in regions that lack the appropriate resources for testing and diagnosis. The high incidence of vitamin C deficiency in resource-limited settings creates a need for an inexpensive, equipment-free, and fast-responding ascorbate detection platform. A detection tool that leverages the natural sensing machinery of bacteria has the potential to meet all of these requirements. l developed two types of Escherichia coli-based biosensors: whole-cell and cell-free. The performance of the two sensors was compared to assess the initial feasibility of each system for field applications.