Flexible integrated black phosphorus sensor arrays for high performance ion sensing

The extraordinary properties of black phosphorus (BP) make it an attracting candidate for next-generation chemical sensors. BP is strain-sensitive due to piezoresistive effect, but the impact of strain on BP chemical sensing performance is still unknown which is critical to flexible devices. Additionally, BP sensor integration is highly desired because of the complexity of real samples, but it remains only theoretically explored. Here, we developed flexible integrated BP sensor arrays (FIBA) functionalized with ionophore, which demonstrated excellent mechanical flexibility (strain limits of 1%) and stability (bending 500 times). Small strain variation (from 0.33% to - 0.16%) resulted in 175% enhancement of sensitivity due to Schottky barrier modulation. Rapid (4 s) label-free detection of 1 mu g/L Hg2+ was achieved, within the permissible limit of the guideline for drinking water quality provided by the World Health Organization (WHO). The low-cost simple-structured FIBA realized multiplexed detection of Hg2+, Cd2+, Pb2+, and Na at trace concentration with excellent selectivity. FIBA also exhibited the ability of monitoring target ions in real samples (Cd2+ in tap water and Na in human sweat). These results demonstrate that FIBA is a promising candidate for wide range of vital signs or environment monitoring.