A touch panel comprising: a substrate having first and second surfaces and edges extending between the first and second surfaces defining a thickness; a first plurality of echelons arranged on the first surface of the substrate in a first array along a first centerline, each echelon in the first plurality of echelons formed at a first angle (α) relative to the first centerline; a first shear transducer mounted on the edge of the substrate, the first transducer configured to generate a shear wave in a source wave mode in a first direction along the first centerline; a second plurality of echelons arranged on the first surface of the substrate in a second array along a second centerline, each echelon in the second plurality of echelons formed at a second angle (α) relative to the second centerline, the second centerline being orthogonal to the first centerline; and a second shear transducer mounted on the edge of the substrate, the second transducer configured to generate a shear wave in a source wave mode in a second direction along the second centerline, wherein the touch panel is arranged so that the shear wave generated by the first shear wave transducer propagates along the first centerline and wherein the shear wave is reflected at the first angle by the one or more of the plurality of echelons in the first array to a first sensing wave or the shear wave is converted to a different wave mode than the source mode, wherein the first sensing wave is reflected off of an edge opposing the first centerline and is sensed by the first transducer, and wherein the touch panel is arranged so that the shear wave generated by the second shear wave transducer propagates along the second centerline and wherein the shear wave is reflected at the second angle by the one or more of the plurality of echelons in the second array to a second sensing wave or the shear wave is converted to a different wave mode than the source mode, wherein the second sensing wave is reflected off of an edge opposing the second centerline and is sensed by the second transducer. a substrate having first and second surfaces and edges extending between the first and second surfaces defining a thickness; a first plurality of echelons arranged on the first surface of the substrate in a first array along a first centerline, each echelon in the first plurality of echelons formed at a first angle (α) relative to the first centerline; a first shear transducer mounted on the edge of the substrate, the first transducer configured to generate a shear wave in a source wave mode in a first direction along the first centerline; a second plurality of echelons arranged on the first surface of the substrate in a second array along a second centerline, each echelon in the second plurality of echelons formed at a second angle (α) relative to the second centerline, the second centerline being orthogonal to the first centerline; and a second shear transducer mounted on the edge of the substrate, the second transducer configured to generate a shear wave in a source wave mode in a second direction along the second centerline, wherein the touch panel is arranged so that the shear wave generated by the first shear wave transducer propagates along the first centerline and wherein the shear wave is reflected at the first angle by the one or more of the plurality of echelons in the first array to a first sensing wave or the shear wave is converted to a different wave mode than the source mode, wherein the first sensing wave is reflected off of an edge opposing the first centerline and is sensed by the first transducer, and wherein the touch panel is arranged so that the shear wave generated by the second shear wave transducer propagates along the second centerline and wherein the shear wave is reflected at the second angle by the one or more of the plurality of echelons in the second array to a second sensing wave or the shear wave is converted to a different wave mode than the source mode, wherein the second sensing wave is reflected off of an edge opposing the second centerline and is sensed by the second transducer.