A substrate for an implanted
microelectrode for implantation into tissue, such as a nerve, or in contact with a single
cell for applying and / or recording electrical signals to and / or from the tissue or single
cell is provided, the substrate comprising a first layer and a second layer deposited on at least a portion of a first surface of the first layer, the first layer and the second layer each extending in the x-direction and the y-direction, the first layer and the second layer stacked in the z-direction, (i) the first layer is based on a first mixture, the first mixture comprising a first component comprising at least one of: (a) a first
photoinitiator, (b) a first
monomer, a first
oligomer, or a first
polymer, the first
monomer, (i) a first component, the first
monomer or first
oligomer or first
copolymer comprising a first functional group, the first functional group being capable of being activated by a first
photoinitiator such that the first component can be photopolymerized via the first functional group; and (ii) the second layer is based on a second mixture, the second mixture comprising: (c) a second
photoinitiator; (d) a second component comprising a second monomer or second
oligomer or second
polymer, the second monomer or second oligomer or second
copolymer comprising a first functional group, the first functional group being capable of being activated by a first photoinitiator such that the first component can be photopolymerized via the first functional group; and a second component, the second oligomer or second
polymer being an acid and comprising a second functional group, the second functional group being capable of being activated by a second photoinitiator such that the second component can be linearly photopolymerized via the second functional group; (e) a base, the base being capable of neutralizing the second monomer or the second oligomer or the second polymer, thereby forming a salt; and (f) a third component comprising at least one of a third oligomer or third polymer, the third oligomer or third polymer comprising two functional groups, the two functional groups being a third functional group and a fourth functional group, each of the third functional group and the fourth functional group being capable of being activated by a second photoinitiator such that the third component can crosslink the second component via the third functional group and the fourth functional group; and wherein the swelling volume of the first layer is less than the swelling volume of the second layer.