1 part per trillion level detection of disinfection byproducts in drinking water using miniaturized sensor

Disinfection byproducts (DBPs) in drinking water, resulting from water disinfecting processes, are harmful to human health even at very low concentrations. It has been challenging to simultaneously realize low-cost, portable, rapid and highly sensitive DBPs detection. Here, we report miniaturized electronic sensors for detecting trace amounts of analytes in water, which are fabricated with covalently modified double-walled carbon nanotubes (DWCNTs). The sensors presented ultrahigh sensitivity to halogenated DBPs, and exhibited a detecting level for dibromoacetic acid (DBAA), a typical halogenated DBPs, of lower than 1 part per trillion (10⁻¹² w/v). The selectivity of the sensors can be tuned by adjusting the functional groups modified on the outer wall of the DWCNTs. The sensor based on amino group-modified DWCNTs showed a selective response to halogenated DBPs. Real-time detection has been further demonstrated by using the device integrated with a microfluidic channel, and the sensor showed a rapid and sensitive response to 10 parts per billion DBAA in aqueous elution. Therefore, this work not only achieved portable, rapid and simple water quality monitoring in daily life, but also, by taking advantage of unique chemical diversity and bilayer structure of functionalized DWCNTs, provided a promising sensor platform especially for trace amount of analytes in solutions.