On‐Chip Multiplexed Voltammetry Using a Universal Antifouling Hydrogel and Porous Gold Foam Interface for Stress and Inflammation Monitoring

Affinity based electrochemical biosensing systems with integrated miniaturized interfaces has enabled key advancement toward rapid, sensitive, precise and deployable detection platforms. Translation of the biosensing tools for routine monitoring of dairy cows' functional welfare through non-invasive methods may have implications for identifying welfare compromise and improving welfare on-farm. The goal is to develop an on-chip voltammetric device to evaluate measures of inflammation and stress in biofluids of dairy cows, that is, milk. The straightforward fabrication of highly reproducible silicon devices designed is demonstrated for an electrochemical interface, using an efficient scale-up process for batch manufacturing of sensitive multiplexed sensor arrays. Lift-off and passivation lithography are used subsequently to construct the electroactive arrays with excellent reproducibility allowing micro and nano-scale patterning. Then the non-specific binding challenge is addressed via a rapid formation of a biocompatible antibiofouling coating onto porous gold surfaces on a single chip - simultaneously - in approximately two minutes. The developed coating provides flexibility in the experimental design due to abundant functional groups (-COOH and -NH2). The coating is combined with glutaraldehyde cross-linked Protein A/G to achieve a universal matrix for Anti-Immunoglobulin G (IgG)-based biosensing and validate by the attainment of two sensors of cortisol and haptoglobin by using milk samples.