Graphene-based micro sensor for continuous chloramine monitoring in water
Ultra-compact, low-cost graphene sensor with selective polymer membrane for real-time, in-line chloramine detection in water systems. Designed to be roughly 1,000 times smaller and 100 times lower cost than existing bulky monitoring equipment, enabling continuous deployment where traditional lab sampling or large instruments are impractical.
Overview
This project delivers a miniature graphene-based sensor platform for continuous, in-line monitoring of chloramine in water. Existing chloramine monitoring approaches rely on off-line laboratory sampling or large, expensive, and complex instrumentation, limiting the frequency and locations where measurements can be made. The proposed solution addresses these gaps by combining a graphene sensing element with a selective polymer membrane that responds specifically to chloramine, enabling accurate detection directly in the water stream.
The technology targets water utilities, industrial process operators, and environmental monitoring programs that need frequent, distributed, and affordable chloramine measurements to maintain disinfection performance and regulatory compliance.
Technical specifications
- Graphene sensing element: microfabricated graphene structures serve as the active transducer, exploiting graphene's sensitivity to surface potential changes.
- Selective polymer membrane: an immobilized polymer coating restricts response to chloramine, improving specificity against common interfering ions such as nitrate, phosphate, sulfate, and chloride.
- Ion-sensitive FET architecture: builds on prior ISFET work in which a chloride-selective membrane demonstrated only minor responses to nitrate, phosphate, and sulfate while producing a measurable Dirac point shift for chloride, indicating the feasibility of selective ion detection.
- Microfabrication: sensors are produced using microfabrication processes, allowing individual sensors or sensor arrays to be produced at the scale of a single rice grain.
- Targeted performance: continuous, in-line operation with a sensing system intended to be at least 1,000 times smaller and at least 100 times lower in cost than currently deployed chloramine monitoring equipment.
Technology readiness level
The membrane selectivity concept has been validated on ISFET platforms using chloride as a model analyte, where interfering ions produced only small responses and the target ion produced a measurable Dirac point shift. The next stage of work focuses on translating this selectivity to chloramine detection on a microfabricated graphene sensor, miniaturizing the full sensing system, and benchmarking size, cost, and accuracy against existing chloramine monitoring equipment. The technology is at an early-to-mid development stage, with core sensing principles demonstrated and device-level chloramine validation and field readiness as the remaining milestones.
About University of Minnesota
The University of Minnesota is a flagship, comprehensive public research university spanning multiple campuses, with a large research enterprise and clinical integration. Industry engages through co-located labs on the Twin Cities campuses, access to an academic health system for clinical translation, and pilot and field-testing facilities that speed scale-up. A statewide extension network and outreach centers provide real-world sites and data partnerships across Minnesota, while proximity to a dense medtech and Fortune 500 corridor enables frequent collaboration. Research is supported by competitive federal funding, including NIH, NSF, DOE, USDA, and DoD. A dedicated technology transfer office manages IP, licensing, sponsored research agreements, and startup incubation to speed commercialization.
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