There are provided nonselective, nonenzymatic electrochemical sensor systems for detection and/or measurement of a redox-active analyte in a liquid sample. Sensor systems comprise a nonenyzmatic electrode system having a working electrode, a counter electrode, and a reference electrode, where the working electrode comprises a nonenzymatic modifier selected to increase sensitivity and/or selectivity of the working electrode for an analyte. Sensor systems are wearable, washable and reusable, and can be used for detection of multiple analytes in a sample.

A biosensor comprising an electrode and inverted molecular pendulums (iMPs) is described. Each IMP includes a linker bound to the electrode, and an analyte receptor and a redox reporter both bound to the linker. The redox reporter is reactive at positive potential when the linker presents a net negative charge and reactive at negative potential when the linker presents a net positive charge. Upon application of an electric field, the biosensor is characterized by an iMPs unbound state, where no analyte is bound to the receptor, at which the iMPs are displaced towards the electrode and electron transfer from the iMPs towards the electrode occurs at an unbound electron transfer rate, and an iMPs bound state, where the analyte is bound to the receptor, at which the iMPs are displaced towards the electrode and electron transfer from the iMPs towards the electrode occurs at a bound electron transfer rate.

An electrochemical microsensor comprising an array of working microelectrodes, the working microelectrodes include: one or more bare microelectrodes; one or more thick film-coated microelectrodes, optionally with conductive additive incorporated into the coating, selected from the group consisting of polysaccharide-coated microelectrodes and platinum black-coated microelectrodes; one or more thin film-coated microelectrodes selected from the group consisting of reduced graphene oxide-coated microelectrode and transition metal chalcogenide-coated microelectrodes; wherein the electrochemical microsensor further comprises a counter electrode and optionally one or more reference microelectrode(s).

Provided is an electrochemical aptasensor for detecting di(2-ethylhexyl)phthalate (DEHP) with high sensitivity. The electrochemical aptasensor according to the present invention has a low detection limit concentration by improving sensitivity by sensor surface modification using a nano composite and gold nanoflowers, and has high practical applicability of a sensor by monitoring a trace amount of DEHP migrating from a real plastic product by a simple measurement method.

A biosensor pixel for measuring current that flows through the electrode surface in response to electrochemical interactions and a biosensor array architecture that includes such biosensor pixels. The biosensor pixel includes an electrode transducer configured to measure a current generated by electrochemical interactions occurring at a recognition layer placed directly on top of it in response to an electrical voltage placed across an electrode transducer-electrolyte interface. The biosensor pixel further includes a trans-impedance amplifier connected to the electrode transducer, where the trans-impedance amplifier is configured to convert the current into a voltage signal as the electrochemical interactions occur. Additionally, the biosensor pixel includes a 1-bit comparator coupled to the trans-impedance amplifier and a 1-bit digital-to-analog converter coupled to the 1-bit comparator, where the 1-bit digital-to-analog converter injects different levels of charge into an input of the trans-impedance amplifier at each cycle based on an output of the 1-bit comparator.

An electrochemical method for detecting hydrogen peroxide includes providing an electrochemical sensor comprising: a container holding an electrolyte; a coated electrode positioned in the container; and a counter electrode spaced apart from the coated electrode in the container, where the coated electrode includes a conductive substrate and a coating comprising a topological insulator on the conductive substrate. A voltage is applied to the coated electrode and the counter electrode, and a biological specimen is added to the electrolyte to form an analyte solution. Current density is measured. An increase in the current density upon forming the analyte solution indicates presence of hydrogen peroxide in the biological specimen.

A coated electrode includes an electrode, a coating configured to immobilize biomolecules, and a coating configured to improve electron transfer rate. Methods of making the coated electrode are also provided. A biosensor comprises a plurality of electrodes, each electrode including the coated electrode.

Systems, devices, and methods are described herein for using a biosensor to detect a target species in a biological sample by electrochemical methods. The systems include a biosensor comprising a working electrode, an anchor layer, a linker, and a recognition component. Optionally, the biosensor can also include a visualization component for characterization of the biosensor by one or more microscopy techniques. In some embodiments, the methods disclosed herein include mixing a reporter molecule with a biological sample to produce a mixture, flowing the resulting mixture over the biosensor, applying an excitation signal to the electrode to initiate a chemical reaction between the reporter molecule, the target species, and the biosensor, sensing a response signal from the biosensor in response to the excitation signal, and determining, based on the response to the excitation signal, the concentration of the target species present in the sample.

The cathodized gold nanoparticle graphite pencil electrode is a sensitive enzymeless electrochemical glucose sensor based on the cathodization of AuNP-GPE. Cyclic voltammetry shows that advantageously, the cathodized AuNP-GPE is able to oxidize glucose partially at low potential (around −0.27 V). Fructose and sucrose cannot be oxidized at <0.1 V, thus the glucose oxidation peak at around −0.27 V is suitable enough for selective detection of glucose in the presence of fructose and sucrose. However, the glucose oxidation peak current at around −0.27 V is much lower which should be enhanced to obtain low detection limit. The AuNP-GPE cathodization increases the oxidation peak current of glucose at around −0.27 V. The dynamic range of the sensor is in the range between 0.05 to 5.0 mM of glucose with good linearity (R.sup.2=0.999). Almost no interference effect was observed for sensing of glucose in the presence of fructose, sucrose and NaCl.

A fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid has a substrate with a first surface configured to face towards the body fluid. The sensor has a working electrode and an interferent electrode. The interferent electrode and the working electrode are electrically separated layers located adjacently on the first surface. The sensor has a further electrode, the further electrode being a counter electrode, a reference electrode or a counter/reference electrode. The working electrode and the interferent electrode each have a layer of a conductive material. The working electrode has an enzyme whereas the interferent electrode is devoid of enzyme. A method for producing the fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid is also disclosed.