Surface Plasmon Resonance Biochemical Sensors Based On The Principle Of Quantum Weak Measurement

Surface Plasmon Resonance(SPR)sensing technology is an optical sensing technology developed in recent decades,due to its label-free and real-time monitoring advantages,has been widely used in food safety,drug and immunoassays.Generally speaking,surface plasmon resonance sensor types mainly include intensity modulation,angle modulation,wavelength modulation and phase modulation of the probing light.In practical applications,due to the existence of noise,the existing SPR sensing technology with different modulation schemes will present different resolution,and the limitation of SPR classical modulation methods,it is difficult to improve the sensitivity and resolution of SPR sensors,and any attempt at such improvements will inevitably bring further cost and complexity to the detection systems.With the rapid development of science and technology and the gradual improvement of people's attention to health and living environment,new and higher requirements are increasingly put upon related detection technologies.Therefore,it is necessary to explore the SPR sensing method and technology based on new principles to break through the limitation of the current SPR sensor resolution,and expand its practical application range.For example,SPR sensing technology can realize trace detection with lower concentration,and even reach the detection level of a few or single molecules;it has a large dynamic range;it can not only the refractive index of the substance can be measured,but also the absolute structure of the molecular can be distinguished.When the above mentioned conditions are realized,if the manufacturing cost of SPR sensor can also be greatly reduced,the portability and easy operation can be realized,and allows a greater processing latitude than the current one,the application of SPR sensor in real life can be greatly promoted.In this dissertation,we combine the principle of quantum weak measurement with SPR sensing technology,making use of the unique advantages of quantum weak measurement that can suppress technical noise while amplify the output signal,thereby greatly improving the resolution and dynamic range of the SPR sensor.In addition,it can also identify the absolute configuration of chiral molecules.The surface plasmon resonance(SPR)sensor based on the principle of quantum weak measurement is not sensitive to the thickness of metal film and noise,in contrast to the traditional SPR sensing technology.Meanwhile,by using intensity modulation the complexity of the system and the manufacturing cost of SPR system are greatly reduced,which renders the operation simple and efficient,thus entailing important application prospects.According to the classification of target substances,e.g.,ionic compounds,organic molecules and chiral molecules,several new SPR sensing configurations based on the principle of quantum weak measurement are proposed.Based on each configuration,systematic measurements are carried out,along with theoretical analysis and experimental studies,and the following innovative results are obtained:(1)An ultrasensitive surface plasmon resonance(SPR)refractive index detection scheme based on the principle of quantum weak measurement is presented,in which linearly polarized light is used as the pre-selected state and intensity modulation is adopted to monitor the ionic compounds(sodium chloride)and achiral molecules(alcohol).Extremely low refractive index change(9.8×10^-7RIU)was readily measurable,with a resolution of a nearly two orders of magnitude increase in sensitivity over conventional SPR index-sensors via intensity interrogation,and the dynamic range is 10^-7?10^-5 RIU.At the same time,the photonic spin Hall phenomenon can be clearly observed with the aid of a CCD detector array.It is found that the interaction between the spin angular momentum and the orbital angular momentum gradually weakens with the increase of the refractive index,until the interaction becomes so weak that the photonic spin Hall Effect can no longer be resolved.The system is highly stable,having a simple and compact configuration,lending to easy and repeatable operation in standard ambient environment.(2)After achieving high-precision detection of the refractive index of ionic compounds and achiral molecules,a novel combination of surface plasmon resonance(SPR)and the principle of quantum weak measurement is further employed and elliptically polarized light is used as the pre-selected stateto measure the refractive index of chiral enantiomers such as sugars and amino acids(glucose,fructose,L-proline,D-proline)by intensity modulation.An extremely low refractive index change of1.13×10^-6 RIU is detected,with a nearly one order of magnitude increase in sensitivity over weak measurement based on a Mach–Zehnder interferometer.Usually,SPR sensors test non-optical-active solutions when the gold film is modified.An important feature is that the system has a simple configuration and is easier to operate than the most sensitive phase-based SPR sensors.It thus paved the way for further exploration of methods for detecting biological molecules such as protein and DNA in aqueous solutions.(3)A surface plasmon resonance sensor of molecular chirality based on quantum weak measurement is suggested,the chiral molecule changes the preselected linear polarization state to test the chiral molecule(glucose,fructose,L-proline,D-proline)optical rotation angle.And the system resolution an order of magnitude higher than the resolution obtained by the intensity modulation quantum weak measurement system,the optical rotation angle changes as low as 2.73×10^-4 rad can be detected.By measuring the change of the output light intensity with the optical rotation angle of the chiral molecule,the absolute configuration of the chiral molecule can be determined according to the intensity direction.The sensoring scheme proposed not only enriches the types of chiral sensors,but also fills the gap that traditional SPR sensors cannot detect the optical rotation of chiral molecules.This method has the unique advantages of real-time monitoring and high resolution for the detection of chiral molecules.At the same time,the system has simple configuration,easy operation and low cost.These features of the precision chirality detection approach make it a useful method that could be employed in diverse life-science applications,such as peptide-based drug synthesis,stereo chemistry,drug analysis,food safety inspection and many other areas where chiral molecules play important roles.(4)Based on the above-mentioned research and design of the high-precision detection sensor for refractive index and optical rotation angle,we further optimized the sensor system,and a multi-functional surface plasmon resonance sensor based on the principle of quantum weak measurement that can simultaneously measure refractive index and optical rotation angle is proposed.The refractive index resolution of this system is 3 orders of magnitude higher than that of the previously proposed scheme that measures the phase based on quantum weak measurement principle adopted the intensity modulation;the resolution of the optical rotation angle higher than the traditional measurement.And this system can identified the absolute configuration of the chiral molecule through the relation between intensity and molecular orientation.This system realized a linear light path with simple operation,excellent stability,and good robustness.This proposed scheme not only realizes the multi-functional applications,but also enriches the types of sensors based on the principle of quantum weak measurement.