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Recently, broken symmetry within crystals has been igniting tremendous research interest since it can be utilized to effectively manipulate the propagation of photons. In particular, low-symmetry Bravais crystals can support hyperbolic shear polaritons (HShPs), holding great promise for technological upgrading on the emerging research area of spinoptics. Herein, an Otto-type multilayer structure consisting of KRS5 prism, sensing medium, and monoclinic β-Ga2O3 crystal is designed to ameliorate the photonic spin Hall effect (PSHE). The surface of β-Ga2O3 is the monoclinic (010) plane (x-y plane). We show that giant spin Hall shifts with three (or two) orders of magnitude of the incident wavelength are obtained in the in-plane (or transverse) directions. The azimuthal dispersions of photonic spin Hall shifts present non‐mirror‐symmetric patterns at tuning the rotation angle of β-Ga2O3 around the z axis in plane. All of these exotic optical properties are closely correlated with the broken crystal lattice symmetry and the incurred excitation of HShPs in monoclinic β-Ga2O3 crystal. By virtue of the remarkably enhanced PSHE, our proposed Otto-type multilayer structure shows a superior biosensing performance in which the maximum sensitivity is two orders of magnitude larger than previously reported PSHE biosensors based on two-dimensional materials. In addition, the optimized physical and structural parameters including the incident angle, excitation wavelength, azimuth angle and doping concentration of β-Ga2O3, thickness and refractive index of sensing medium are also investigated and given. This work unequivocally confirms the strong influence of crystal symmetry on the PSHE, shedding important insights into understanding the rich modulation of spin-orbit interaction of light via shear polaritons and therefore facilitating potential applications in photoelectronic devices.