Evaluation of Shear Horizontal Surface Acoustic Wave Biosensors Using “Layer Parameter” Obtained from Sensor Responses during Immunoreaction

Abstract

Shear horizontal surface acoustic wave (SH-SAW) biosensors measure the reaction of capture antibodies immobilized on the sensing surface to capture test molecules (antigens) by using the change in SH-SAW propagation characteristics. SH-SAW displacement exists not only on the SH-SAW propagating surface, but also partially penetrates the specimen liquid to a certain depth, which is determined by the liquid properties of the specimen and the operating frequency of the SH-SAW. This phenomenon is called viscosity penetration. In previous studies, the effect of viscosity penetration was not considered in the measurement of SH-SAW biosensors, and the mass or viscosity change caused by the specific binding of capture antibodies to the target antigen was mainly used for the measurement. However, by considering the effect of viscosity penetration, it was found that the antigen–antibody reaction could be measured and the detection characteristics of the biosensor could be improved. Therefore, this study aims to evaluate the detection properties of SH-SAW biosensors in the surface height direction by investigating the relationship between molecular dimensions and SH-SAW propagation characteristics, which are pseudo-changed by varying the diameter of gold nanoparticles. For the evaluation, we introduced a layer parameter defined by the ratio of the SH-SAW amplitude change to the SH-SAW velocity change caused by the antigen–antibody reaction. We found a correlation between the layer parameter and pseudo-varied molecular dimensions. The results suggest that SH-SAW does not only measure the mass and viscosity but can also measure the size of the molecule to be detected. This shows that SH-SAW biosensors can be used for advanced functionality.

A Novel Rapid Test to Detect Anti-SARS-CoV-2 N Protein IgG Based on Shear Horizontal Surface Acoustic Wave (SH-SAW)

“…The binding kinetic analysis can help to further improve the measurement accuracy, in addition to monitoring the sensor output changes. Study is ongoing on the binding curves of the SH-SAW sensor system [36,37].…”

Application of Shear Horizontal Surface Acoustic Wave (SH-SAW) Immunosensor in Point-of-Care Diagnosis

“…In this review, a three-layer model as shown in Figure 3 b was used to calculate the glycerol-water mixture. The substrate layer (I) is 36Y-90X quartz, the metal layer (II) is gold, and the liquid layer (III) is a glycerol-water mixture [ 35 , 36 ]. In these calculations, we used an improved numerical computational method for these model structures [ 31 , 34 , 36 ].…”

“…The substrate layer (I) is 36Y-90X quartz, the metal layer (II) is gold, and the liquid layer (III) is a glycerol-water mixture [ 35 , 36 ]. In these calculations, we used an improved numerical computational method for these model structures [ 31 , 34 , 36 ]. This method was modified from two computational methods: one is based on Campbell and Jones [ 37 ], and the other is based on Moriizumi, Unno and Shiokawa [ 38 ].…”

“…We used the following values in our calculations, as shown in Table 1 . This numerical calculation method [ 31 , 34 , 36 ] is very adequate for SH-SAW sensor devices on quartz. On the other hand, another analytical model for SH-SAW devices using FEM (Finite Element Method) will be investigated in the near future.…”

Development of Simple and Portable Surface Acoustic Wave Biosensors for Applications in Biology and Medicine

“…Several technologies have been explored including Mass spectrometry field [4,5], electrochemical sensors field [6], optical detection field [7,8], surface plasmon resonance spectroscopy field [9], and interferometry [10,11] but each has significant limitations in complex biological matrices. The SAW biosensor technology is based on Surface acoustic waves (SAW), a type of acoustic wave that propagates along a surface of a solid material [12][13][14]. Propagating SAW are impacted by mass loading and changes in viscoelastic properties of the media on the surface of the sensor and compared to a reference, as seen in Figure 1a and b [15].…”