A memory device (20, 30, 40), comprising: a substrate (21, 31, 41) comprising a first substrate surface (21c, 31c, 41c), a second substrate surface (21d, 31d, 41d) opposite to the first substrate surface (21c, 31c, 41c), and a first lateral side (21a, 31a, 41a) and a second lateral side (21b, 31b, 41b), which are arranged between the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d) and opposite to each other, and further comprising: a storage module (213, 313); plural light-emitting elements (212, 312, 412) disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d); and a connection interface (211, 311, 411) comprising a first connection part (2111, 3111, 4111) and a second connection part (2112, 3112, 4112), wherein the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are respectively disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d) of the substrate (21, 31, 41), and the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are located adjacent the first lateral side (21a, 31a, 41a) of the substrate (21, 31, 41) and configured to be electrically connected to an electronic device; a heat dissipation structure (231, 232, 331, 332, 431, 432) partially connected with the substrate (21, 31, 41), at least one channel being formed between said heat dissipation structure (231, 232, 331, 332, 431, 432) and the substrate (21, 31, 41); and a light guide element (24, 34, 44) assembled with or locked on the heat dissipation structure (231, 232, 331, 332, 431, 432), wherein the light guide element (24, 34, 44) is located adjacent the second lateral side (21b, 31b, 41b) of the substrate (21, 31, 41), and separated from the plural light-emitting elements (212, 312, 412) by the heat dissipation structure (231, 232, 331, 332, 431, 432), and wherein the light guide element (24, 34, 44) is configured so that after light beams generated by the plural light-emitting elements (212, 312, 412) pass through the at least one channel, the light beams are centralized or distributed on the light guide element (24, 34, 44). a substrate (21, 31, 41) comprising a first substrate surface (21c, 31c, 41c), a second substrate surface (21d, 31d, 41d) opposite to the first substrate surface (21c, 31c, 41c), and a first lateral side (21a, 31a, 41a) and a second lateral side (21b, 31b, 41b), which are arranged between the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d) and opposite to each other, and further comprising: a storage module (213, 313); plural light-emitting elements (212, 312, 412) disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d); and a connection interface (211, 311, 411) comprising a first connection part (2111, 3111, 4111) and a second connection part (2112, 3112, 4112), wherein the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are respectively disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d) of the substrate (21, 31, 41), and the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are located adjacent the first lateral side (21a, 31a, 41a) of the substrate (21, 31, 41) and configured to be electrically connected to an electronic device; a storage module (213, 313); plural light-emitting elements (212, 312, 412) disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d); and a connection interface (211, 311, 411) comprising a first connection part (2111, 3111, 4111) and a second connection part (2112, 3112, 4112), wherein the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are respectively disposed on the first substrate surface (21c, 31c, 41c) and the second substrate surface (21d, 31d, 41d) of the substrate (21, 31, 41), and the first connection part (2111, 3111, 4111) and the second connection part (2112, 3112, 4112) are located adjacent the first lateral side (21a, 31a, 41a) of the substrate (21, 31, 41) and configured to be electrically connected to an electronic device; a heat dissipation structure (231, 232, 331, 332, 431, 432) partially connected with the substrate (21, 31, 41), at least one channel being formed between said heat dissipation structure (231, 232, 331, 332, 431, 432) and the substrate (21, 31, 41); and a light guide element (24, 34, 44) assembled with or locked on the heat dissipation structure (231, 232, 331, 332, 431, 432), wherein the light guide element (24, 34, 44) is located adjacent the second lateral side (21b, 31b, 41b) of the substrate (21, 31, 41), and separated from the plural light-emitting elements (212, 312, 412) by the heat dissipation structure (231, 232, 331, 332, 431, 432), and wherein the light guide element (24, 34, 44) is configured so that after light beams generated by the plural light-emitting elements (212, 312, 412) pass through the at least one channel, the light beams are centralized or distributed on the light guide element (24, 34, 44).