A micro-electromechanical systems (MEMS) device comprising: a substrate comprising at least one anchor; a proof mass (12, 54, 56, 102) comprising at least one deceleration extension (66, 100) extending from said proof mass (12, 54, 56, 102); a motor drive comb; a motor sense comb; a plurality of suspensions configured to suspend said proof mass (12, 54, 56, 102) over said substrate and between said motor drive comb and said motor sense comb, said suspensions anchored to said substrate; a body (60, 126) attached to said substrate; and at least two deceleration beams (64, 128) extending from said body (60, 126), said deceleration beams (64, 128) configured to engage said at least one deceleration extension (66, 100) and to slow or stop said proof mass (12, 54, 56, 102) before said proof mass contacts said motor drive comb and said motor sense comb; wherein said deceleration extensions (66, 100) and said deceleration beams (64, 128) are configured to bend when engaged and provide the deceleration function for said proof mass (12, 54, 56, 102); and characterised in that said substrate comprises at least one raised area configured to engage said deceleration extension (66, 100) said raised area configured to reduce or eliminate contact between said proof mass (12, 54, 56, 102) and components of said device under said proof mass; wherein said at least one deceleration extension (66, 100) comprises: a top surface; and at least one raised area on said top surface, said raised areas configured to reduce or eliminate contact between said proof mass (12, 54, 56, 102) and components of said device above said proof mass. a substrate comprising at least one anchor; a proof mass (12, 54, 56, 102) comprising at least one deceleration extension (66, 100) extending from said proof mass (12, 54, 56, 102); a motor drive comb; a motor sense comb; a plurality of suspensions configured to suspend said proof mass (12, 54, 56, 102) over said substrate and between said motor drive comb and said motor sense comb, said suspensions anchored to said substrate; a body (60, 126) attached to said substrate; and at least two deceleration beams (64, 128) extending from said body (60, 126), said deceleration beams (64, 128) configured to engage said at least one deceleration extension (66, 100) and to slow or stop said proof mass (12, 54, 56, 102) before said proof mass contacts said motor drive comb and said motor sense comb; wherein said deceleration extensions (66, 100) and said deceleration beams (64, 128) are configured to bend when engaged and provide the deceleration function for said proof mass (12, 54, 56, 102); and characterised in that said substrate comprises at least one raised area configured to engage said deceleration extension (66, 100) said raised area configured to reduce or eliminate contact between said proof mass (12, 54, 56, 102) and components of said device under said proof mass; wherein said at least one deceleration extension (66, 100) comprises: a top surface; and at least one raised area on said top surface, said raised areas configured to reduce or eliminate contact between said proof mass (12, 54, 56, 102) and components of said device above said proof mass. a top surface; and at least one raised area on said top surface, said raised areas configured to reduce or eliminate contact between said proof mass (12, 54, 56, 102) and components of said device above said proof mass.