An angular velocity sensor comprising: an insulative support layer ; a substrate layer comprising a planar ring structure mounted to vibrate in-plane; and a plurality of conductive electrodes , each electrode comprising a first set of moveable conductive electrode tracks formed on a surface of the planar ring structure and a second set of fixed conductive electrode tracks ; wherein the first and second sets of conductive electrode tracks are interdigitated with a lateral spacing between each moveable conductive electrode track and an adjacent fixed conductive electrode track in a radial direction of the planar ring structure , and wherein each of the moveable conductive electrode tracks has a radial offset from a median line between adjacent fixed conductive electrode tracks such that each moveable conductive electrode track has a first lateral spacing from an adjacent fixed conductive electrode track in a first radial direction and a second, different lateral spacing from an adjacent fixed conductive electrode track in a second opposite radial direction characterised in that : the substrate layer is formed of a silica-based material; and the second set of fixed conductive electrode tracks is formed on a surface of the insulative support layer that is facing the surface of the planar ring structure and that is axially spaced from said surface of the planar ring structure by a gap in an axial direction normal to the planar ring structure . an insulative support layer ; a substrate layer comprising a planar ring structure mounted to vibrate in-plane; and a plurality of conductive electrodes , each electrode comprising a first set of moveable conductive electrode tracks formed on a surface of the planar ring structure and a second set of fixed conductive electrode tracks ; wherein the first and second sets of conductive electrode tracks are interdigitated with a lateral spacing between each moveable conductive electrode track and an adjacent fixed conductive electrode track in a radial direction of the planar ring structure , and wherein each of the moveable conductive electrode tracks has a radial offset from a median line between adjacent fixed conductive electrode tracks such that each moveable conductive electrode track has a first lateral spacing from an adjacent fixed conductive electrode track in a first radial direction and a second, different lateral spacing from an adjacent fixed conductive electrode track in a second opposite radial direction characterised in that : the substrate layer is formed of a silica-based material; and the second set of fixed conductive electrode tracks is formed on a surface of the insulative support layer that is facing the surface of the planar ring structure and that is axially spaced from said surface of the planar ring structure by a gap in an axial direction normal to the planar ring structure . the substrate layer is formed of a silica-based material; and the second set of fixed conductive electrode tracks is formed on a surface of the insulative support layer that is facing the surface of the planar ring structure and that is axially spaced from said surface of the planar ring structure by a gap in an axial direction normal to the planar ring structure . <EOS>