Design and implementation of an open-access arsenic biosensor.

Arsenic contamination in groundwater is a critical global issue, affecting over 140 million people worldwide and posing severe public health risks, particularly in low-resource and rural communities. Argentina alone has approximately 4 million people exposed to arsenic. The measurement of arsenic in private wells is often limited by high costs, specialized personnel requirements, and geographical distances to analytical laboratories. In this paper, we describe the design and implementation of a portable, open-access arsenic biosensor that combines synthetic biology and industrial design. The biosensor employs genetically modified Escherichia coli and a colorimetric readout to detect arsenic concentrations as low as 5 µg/L. Validation studies on 61 samples yielded a sensitivity of 98.1% and specificity of 99.0%. By using paper-based, dehydrated bacterial modules and a 3D-printed housing, this device is cost-effective, easy to use, and amenable to replication in low-resource settings. In addition, the open-access approach ensures that critical knowledge such as plasmid sequences, device schematics, and protocols can be freely shared and locally adapted. Beyond the technical advantages, this biosensor can potentially influence global policies and Argentinian programs on water quality monitoring, empowering communities to take charge of arsenic surveillance and safeguard public health.