Multiplex electrochemical biosensors have been used for eliminating the matrix effect in complex bodily fluids or enabling the detection of two or more bioanalytes, overall resulting in more sensitive assays and accurate diagnostics. Many electrochemical biosensors lack reliable and low-cost multiplexing to meet the requirements of point-of-care detection due to either limited functional biosensors for multi-electrode detection or incompatible readout systems. We developed a new dual electrochemical biosensing unit accompanied by a customized potentiostat to address the unmet need for point-of-care multi-electrode electrochemical biosensing. The two-working electrode system was developed using screen-printing of a carboxyl-rich nanomaterial containing ink, with both working electrodes offering active sites for recognition of bioanalytes. The low-cost bi-potentiostat system (∼$80) was developed and customized specifically to the bi-electrode design and used for rapid, repeatable, and accurate measurement of electrochemical impedance spectroscopy signals from the dual biosensor. This binary electrochemical data acquisition (Bi-ECDAQ) system accurately and selectively detected SARS-CoV-2 Nucleocapsid protein (N-protein) in both spiked samples and clinical nasopharyngeal swab samples of COVID-19 patients within 30 min. The two working electrodes offered the limit of detection of 116 fg/mL and 150 fg/mL, respectively, with the dynamic detection range of 1–10,000 pg/mL and the sensitivity range of 2744–2936 Ω mL/pg.mm 2 for the detection of N-protein. The potentiostat performed comparable or better than commercial Autolab potentiostats while it is significantly lower cost. The open-source Bi-ECDAQ presents a customizable and flexible approach towards addressing the need for rapid and accurate point-of-care electrochemical biosensors for the rapid detection of various diseases.

Optimized self-contained microfluidic platform allows for single-step detection of proteins, through passive delivery of the dry-stored reagents required for immunosensing. Novel autonomous performance of the platform advances the point-of-care utilization of electrochemical protein sensing.

The scope of this paper is to present a fuzzy logic control of a class of multi-input multioutput (MIMO) nonlinear systems called “system of ball on a sphere,” such an inherently nonlinear, unstable, and underactuated system, considered truly to be two independent ball and wheel systems around its equilibrium point. In this work, Sugeno method is investigated as a fuzzy controller method, so it works in a good state with optimization and adaptive techniques, which makes it very attractive in control problems, particularly for such nonlinear dynamic systems. The system’s dynamic is described and the equations are illustrated. The outputs are shown in different figures so as to be compared. Finally, these simulation results show the exactness of the controller’s performance.

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In this paper a dynamical model and the governing equations of motion of a micro-cantilever beam with rotating joint as an application of under-actuated systems will be developed. The model is based on the geometrically nonlinear equations of motion of the microbeam, employing strain gradient elasticity theory. The Rayleigh–Ritz method is used to discretize partial differential equations to obtain a set of nonlinear ordinary differential equations of motion. Then, a controlled Lagrangian method as a robust procedure for controller design is employed to achieve an acceptable tracking on the hinge’s angle of rotation of a micro-cantilever beam while undesirable vibration of the under-actuated flexible variable is damped. A stability analysis of the closed-loop system is also discussed. The advantages of the controlled Lagrangian method lie in its ability to find the Lyapunov function to prove the stability of the system and its capability of handling under-actuated devices. The performance of the designed control scheme is illustrated through several numerical simulation results and some comparisons are made in various situations.