A differential temperature measuring device comprising: - a first piezoelectric substrate made of a single crystal of lanthanum gallium silicate on which is arranged a first surface transverse wave resonator having a first predetermined resonance configuration, - a second piezoelectric substrate made of a single crystal of lanthanum gallium silicate on which is arranged a second surface transverse wave resonator having a second predetermined resonance configuration identical to said first predetermined resonance configuration, wherein said first piezoelectric substrate has a double-rotation cut which is different from the double-rotation cut angle of said second piezoelectric substrate, characterized in that when said first piezoelectric substrate has a crystalline orientation defined by a X 1, Y 1, Z 1 crystal axis set, said first surface acoustic wave resonator comprises in a plane defined by the X 1, Z 1 axes an array of electrodes whose orientation is parallel with respect to the X 1 crystal axis and perpendicular with respect to the Z 1 crystal axis, when said second piezoelectric substrate has a crystalline orientation defined by X 2, Y 2, Z 2 crystal axis set, said second surface acoustic wave resonator comprises in a plane defined by the X 2, Z 2 axes an array of electrodes whose orientation is parallel with respect to the X 2 crystal axis and perpendicular with respect to the Z 2 crystal axis, said array of electrodes of each of said first and second surface acoustic wave resonators having: - a relative thickness that satisfies the following equality: 0.5% < h/λ ac < 13% with: h the thickness of electrodes of said first and second surface acoustic wave resonators, λ ac the acoustic wavelength of said first and second surface acoustic wave resonators; - a relative metallisation ratio that satisfies the following equality: 0.3 < a/p < 0.7 with: a the width of the electrodes of said first and second surface acoustic wave resonators; p the mechanical period of said array of electrodes. - a first piezoelectric substrate made of a single crystal of lanthanum gallium silicate on which is arranged a first surface transverse wave resonator having a first predetermined resonance configuration, - a second piezoelectric substrate made of a single crystal of lanthanum gallium silicate on which is arranged a second surface transverse wave resonator having a second predetermined resonance configuration identical to said first predetermined resonance configuration, - a relative thickness that satisfies the following equality: 0.5% < h/λ ac < 13% with: h the thickness of electrodes of said first and second surface acoustic wave resonators, λ ac the acoustic wavelength of said first and second surface acoustic wave resonators; h the thickness of electrodes of said first and second surface acoustic wave resonators, λ ac the acoustic wavelength of said first and second surface acoustic wave resonators; - a relative metallisation ratio that satisfies the following equality: 0.3 < a/p < 0.7 with: a the width of the electrodes of said first and second surface acoustic wave resonators; p the mechanical period of said array of electrodes. a the width of the electrodes of said first and second surface acoustic wave resonators; p the mechanical period of said array of electrodes.