Abstract: Flexible fuel cell sensors and methods of making and using the same are provided. A fuel cell sensor can be used for the detection of, for example, isopropyl alcohol (IPA), and the working mechanism of the fuel cell sensor can rely on redox reactions. The fuel cell sensor can include a proton exchange membrane (PEM), an anode disposed on a first surface of the PEM, a cathode disposed on a second surface of the PEM opposite from the first surface, and a reference electrode disposed on the first surface of the PEM and spaced apart from the anode.

Abstract: Continuous monitoring of acetone is a challenge using related art sensing methods. Though real-time detection of acetone from different biofluids is promising, signal interference from other biomarkers remains an issue. A minor fluctuation of the signals in the micro-ampere range can cause substantial overlapping in linear/polynomial calibration fittings. To address the above in non-invasive detection, principal component analysis (PCA) can be used to generate specific patterns for different concentration points of acetone in the subspace. This results in improvement of the problem of overlapping of the signals between two different concentration points of the data sets while eliminating dimensionality and redundancy of data variables. An algorithm following PCA can be incorporated in a microcontroller of a sensor, resulting in a functional wearable acetone sensor. Acetone in the physiological range (0.5 ppm to 4 ppm) can be detected with such a sensor.

Abstract: Continuous monitoring of acetone is a challenge using related art sensing methods. Though real-time detection of acetone from different biofluids is promising, signal interference from other biomarkers remains an issue. A minor fluctuation of the signals in the micro-ampere range can cause substantial overlapping in linear/polynomial calibration fittings. To address the above in non-invasive detection, principal component analysis (PCA) can be used to generate specific patterns for different concentration points of acetone in the subspace. This results in improvement of the problem of overlapping of the signals between two different concentration points of the data sets while eliminating dimensionality and redundancy of data variables. An algorithm following PCA can be incorporated in a microcontroller of a sensor, resulting in a functional wearable acetone sensor. Acetone in the physiological range (0.5 ppm to 4 ppm) can be detected with such a sensor.

Abstract: A sensor, a method for its fabrication, and a method for its use to detect contaminants, for example, ammonia, in stagnant and dynamic fluid media, especially liquid media. The sensor is an opto-chemical sensor that includes a polymer optical fiber, a sensing layer comprising oxazine 170 perchlorate on the polymer optical fiber, and a membrane layer on the sensing layer. The membrane layer is gas permeable and not permeable to the fluid in the fluid system, and moisture is entrapped by and between the sensing and membrane layers.

Abstract: A sensor, a method for its fabrication, and a method for its use to detect contaminants, for example, ammonia, in stagnant and dynamic fluid media, especially liquid media. The sensor is an opto-chemical sensor that includes a polymer optical fiber, a sensing layer comprising oxazine 170 perchlorate on the polymer optical fiber, and a membrane layer on the sensing layer. The membrane layer is gas permeable and not permeable to the fluid in the fluid system, and moisture is entrapped by and between the sensing and membrane layers.