An ultra-sensitive biosensor based on surface plasmon resonance and weak value amplification.

An ultra-sensitive phase plasmonic sensor combined with weak value amplification is proposed for the detection of IgG, as a model analyte. Phase detection is accomplished by self-interference between the p-polarization and the s-polarization of the light. With the principles of weak value amplification, a phase compensator is used to modulate the coupling strength and enhance the refractive index sensitivity of the system. On a simple Au-coated prism-coupled surface plasmon resonance (SPR) structure, the scheme, called WMSPR, achieves a refractive index sensitivity of 4.737 × 104 nm/RIU, which is about three times higher than that of the conventional phase-based approach. The proposed WMSPR biosensor gives great characteristics with a high resolution of 6.333 × 10-8 RIU and a low limit of detection (LOD) of 5.3 ng/mL. The results yield a great scope to promote the optimization of other SPR biosensors for high sensitivity.

Ultra-precise weak measurement-based interfacial biosensors.

In this study, an interfacial biosensing scheme with ultra-precision is proposed. The scheme uses weak measurement techniques to ensure ultra-high sensitivity of the sensing system while improving the stability of the system through self-referencing and pixel point averaging, thus achieving ultra-high detection accuracy of biological samples. In specific experiments, we have used the biosensor in this study to perform specific binding reaction experiments for protein A and Mouse IgG with a detection line of 2.71 ng/mL for IgG. In addition, the sensor is non-coated, simple in structure, easy to operate, and low in cost of use.

In Situ Detection of Electrochemical Reaction Surface Area by Optical Weak Measurement.

The surface area is key to electrochemical systems, including those in electrocatalysis and energy storage. Studies have shown that the surface area of the electrocatalyst directly affects the electrochemical activity, adsorption performance, and stability of the electrocatalyst. This paper used an optical weak measurement (WM) method, which has little impact on the analyte, to measure the reaction surface area (RSA) that actually participated in the electrochemical reaction. Then compared the RSA obtained by the WM with the total surface area (TSA) obtained by the standard Brunauer-Emmett-Teller (BET) measurement and the active surface area (ASA) obtained by the electrochemical double-layer capacitance (EDLC) method. Their growth trend was consistent, indicating the reliability of the WM method. Compared with the above two methods, the WM method is an in situ detection and easy to operate experimentally, which can help researchers to consider the effect of surface area on electrocatalyst performance more rationally.

Demonstration of a New Characterization Method for Weak Measurement.

In this work, the difference between the weak measurement method and the weak value amplification process and the classical measurement process is thoroughly discussed, and the transition conditions of the weak value enhancement are obtained. A transition mode of the weak measurement and the classical measurement is proposed for the first time, and a better fitting model of the measurement results is found by performing a systematic analysis. On top of that, the importance of the new fitting method for the application of the weak measurement system is verified during the industrial production of organic molecular -nucleic acid, protein, polysaccharide-hydrolysis or synthesis. At the same time, a variety of spectral characterization methods are proposed and the advantages and disadvantages of the different characterization methods are analyzed through carrying out experiments. Consequently, the wide implementation of weak measurement-based detection technology is attained.

Imaging Sensor for the Detection of the Flow Battery Via Weak Value Amplification.

Flow battery electrodes are vital for performing redox reactions, and an in-depth understanding of reaction kinetics and spatial distribution differences in electrodes is very important for improving the efficiency of electrochemical reactions. In this study, a reflection-type phase-sensitive weak measurement imaging system was developed for the detection of flow batteries. The phase difference between two polarization components in total internal reflection caused by electrode redox processes was measured by weak value amplification. The resulting refractive index resolution of the imaging system was estimated to be 2.8-4.2 × 10-6 RIU. The real-time monitoring ability of the system was demonstrated by linear sweep voltammetry tests of vanadium redox batteries. Compared to traditional optical methods, the proposed weak measurement imaging sensor did not require coating, as it can be used in acid electrolytes of vanadium flow batteries. Meanwhile, the weak value amplification effect led to a higher resolution than the total internal reflection system shown in our previous work, thereby resulting in more accurate detection of electrochemical reactions. In sum, the proposed sensor looks very promising for the detection of electrochemical reactions in flow batteries, water splitting, electrochemical corrosion, and electrocatalysis.

Specific detection of glucose by an optical weak measurement sensor.

Diabetes is an important public health problem and finding quick testing methods with high accuracy, reliability, and convenience are important to control the blood glucose of diabetic patients. In this study, a sensor based on a weak measurement scheme was developed for the specific detection of glucose for the first time. The detection of glucose using the proposed method was completed by the high sensitivity and resolution of the weak measurement based on optical rotation detection, as well as the change in the optical rotation before and after the specific oxidation of glucose. The resolution of the as-obtained glucose sensor was around 2.71×10-3 g/L (1.50×10-2 mmol/L), and the detection range was 0-11 g/L (0-61 mmol/L).

In situ detection of electrochemical reaction by weak measurement.

In the field of electrochemical energy storage systems, the use of in situ detection technology helps to study the mechanism of electrochemical reaction. Our group has previously in situ detected the electrochemical reaction in vanadium flow batteries by total internal reflection (TIR) imaging. In order to further improve the detection resolution, in this study, the weak measurement (WM) method was introduced to in situ detect the electrochemical reaction during the linear sweep voltammetry or the cyclic voltammetry tests with quantitative measurement of the absolute current density, which lays a foundation for replacing the TIR for two-dimensional imaging of electrochemical reactions in vanadium flow batteries, oxygen/hydrogen evolution reaction, surface treatments, electrochemical corrosion and so on.

Weak measurement-based sensor for the rapid identification of L(+)-ascorbic acid and D(-)-isoascorbic acid.

The ability to identify L(+)-ascorbic acid from D(-)-isoascorbic acid in medicinal products is of practical interest. Based on the method of frequency domain weak measurement, a set of common optical path sensors for identification of L(+)-ascorbic acid and D(-)-isoascorbic acid is established. By quantificationally analyzing the magnitude and offset direction of the spectral central wavelength, a good identification of the concentration and the optically active forms of ascorbic acid has been achieved. The sensitivity and resolution of the sensor for optical rotation can reach 34.35 nm/° and ${5.53} \times {{10}^{ - 5}}^\circ $5.53×10-5 ∘, respectively. The detection resolution for L(+)-ascorbic acid is ${2.00} \times {{10}^{ - 4}}\;{\rm mol}/{\rm mL}$2.00×10-4mol/mL, and that for D(-)-isoascorbic acid is ${2.73} \times {{10}^{ - 4}}\;{\rm mol}/{\rm mL}$2.73×10-4mol/mL. The potential of the sensor in the detection of transparent but optically inactive impurities has been verified by comparative experiments of sodium chloride solution. The sensor also has been applied to identify medicinal vitamin C tablets, which verified the feasibility of the method in optically active pharmaceutical solutions with water-insoluble, optically inactive impurities. Since the sensor has the advantages of high precision, real-time, high robustness, and being non-destructive, it has a great prospect in the field of drug detection containing chiral molecules.