Autonomous electrochemical biosensors: A new vision to direct methanol fuel cells

A passive direct methanol fuel cell as transducer of an electrochemical sensor, applied to the detection of carcinoembryonic antigen

This work describes an electrochemical sensor with a biomimetic plastic antibody film for carcinoembryonic antigen (CEA, an important biomarker in colorectal cancer), integrated in the electrical circuit of a direct methanol fuel cell (DMFC), working in passive mode and used herein as power supply and signal transducer. In detail, the sensing layer for CEA consisted of a Fluorine-doped Tin Oxide (FTO) conductive glass substrate - connected to the negative pole side of the DMFC - with a conductive poly (3,4-ethylenedioxythiophene) (PEDOT) layer and a polypyrrol (PPy) molecularly-imprinted polymer (MIP), assembled in-situ. This sensing element is then closed using a cover FTO-glass, hold in place with a clip, connected to the positive side of the DMFC. When compared with control DMFCs, the power curves of DMFC/Sensor integrated system showed decreased power values due to the MIP layer interfaced in the electrical circuit, also displaying high stability signals. The DMFC/Sensor was further calibrated at room temperature, in different medium (buffer, a synthetic physiological fluid model and Cormay® serum), showing linear responses over a wide concentration range, with a limit of detection of 0.08 ng/mL. The DMFC/Sensor presented sensitive data, with linear responses from 0.1 ng/mL to 100 μg/mL and operating well in the presence of human serum. Overall, the results obtained evidenced the possibility of using a DMFC as a transducing element in an electrochemical sensor, confirming the sensitive and selective readings of the bio (sensing) imprinted film. This integration paves the way towards fully autonomous electrochemical devices, in which the integration of the sensor inside the fuel cell may be a subsequent direction.

Self-Powered Portable Electronic Reader for Point-of-Care Amperometric Measurements

In this work, we present a self-powered electronic reader (e-reader) for point-of-care diagnostics based on the use of a fuel cell (FC) which works as a power source and as a sensor. The self-powered e-reader extracts the energy from the FC to supply the electronic components concomitantly, while performing the detection of the fuel concentration. The designed electronics rely on straightforward standards for low power consumption, resulting in a robust and low power device without needing an external power source. Besides, the custom electronic instrumentation platform can process and display fuel concentration without requiring any type of laboratory equipment. In this study, we present the electronics system in detail and describe all modules that make up the system. Furthermore, we validate the device’s operation with different emulated FCs and sensors presented in the literature. The e-reader can be adjusted to numerous current ranges up to 3 mA, with a 13 nA resolution and an uncertainty of 1.8%. Besides, it only consumes 900 µW in the low power mode of operation, and it can operate with a minimum voltage of 330 mV. This concept can be extended to a wide range of fields, from biomedical to environmental applications.

A novel fluorescent functional monomer as the recognition element in core–shell imprinted sensors responding to concentration of 2,4,6-trichlorophenol

We have demonstrated a fluorescent functional monomer instead of the traditional functional monomers for molecularly imprinted sensors. The sensors were firstly used to selectively detect 2,4,6-trichlorophenol (2,4,6-TCP) by solid fluorescence detection without a dispersion solution. Moreover, the selectivity and anti-interference ability of the SiO₂@dye-FMIPs sensor meet the requirements of a fluorescent sensor. The novel fluorescent monomer introduced into MIP is no longer just a fluorophore without recognizing ability. The fluorescence intensity of SiO₂@dye-FMIPs showed a linear response to 2,4,6-TCP concentration in the range of 0–100 nM with a detection limit of 0.0534 nM. We could also demonstrate that such a system can not only get rid of the confines of traditional functional monomers and detection manner, but also improved the applications of MIPs sensors in sensing systems.

We have demonstrated a molecularly imprinted sensor with a fluorescent functional monomer instead of the traditional functional monomers to detect 2,4,6-TCP.