Low-cost sensors for real-time monitoring of contaminants in water, such as toxic heavy metal ions, could provide early warning of contamination, thereby improving drinking water safety and protecting public health. A graphene-based water sensor platform is thus explored for rapid, sensitive, and selective detection of various water contaminants, overcoming limitations of current sensing technologies such as slow detection and inadequate sensitivity. However, the commercialization of such a sensor system is limited by its relatively high manufacturing cost due to the batch processing that involves traditional lithographic electrode fabrication and multiple manual post-electrode fabrication processes. This award explores a low-cost customized inkjet printing process for manufacturing of graphene-based water sensors. The research entails engineering various inks and modifying the standard inkjet printing process to produce the complete sensor system, continuously. High throughput manufacturing of the nano-enabled water sensing systems reduces their cost and enhances market acceptance. The research outcomes provide the rationale for substrate selection and treatment, scalable methods for producing various inks suitable for inkjet printing, and process models for customized inkjet printing. Project results could be used for many other applications such as solar cells, lithium-ion batteries, and supercapacitors, enabling low-cost manufacturing of a wide range of printable electronic devices. The project trains diverse student populations including women and minorities on scalable nanomanufacturing, nanodevice design and real-time water-sensing technologies through hands-on research experience, a course module, and enriching existing curricula.
The sensor platform is based on a field-effect transistor structure with reduced graphene oxide as the sensing channel and gold nanoparticles as anchoring sites of selective chemical probes. A major challenge for inkjet printing is the customization of the inkjet printing process for a specific device or system architecture. Customization involves engineering suitable inks, modifying the standard printing process parameters, and integrating components at different scales. The research team aims to close this knowledge gap by exploring inkjet printing of the entire graphene-based sensor system to enable the large-scale production via high throughput roll-to-roll nanomanufacturing of the sensor devices, which should result in low cost. The scalable nanomanufacturing of inks for all sensor components: electrode, sensing material, and probe, and their printing and integration into water sensor systems are investigated, together with methods for selecting and treating polymer substrates and customizing inkjet printing parameters. The sensor performance is validated in industrial testbeds through collaboration with A. O. Smith Corporation and NanoAffix Science, LLC. The project leads to a low-cost, high-yield scalable nanomanufacturing platform for graphene-based water sensor systems and other flexible electronic systems that can be readily commercialized by industrial partners.