A device for communication, the device comprising: a system (12a, 30, 40) comprising: a support structure (32, 42); a partial power source comprising: a first material (34, 44) deposited onto the support structure; and a second material (36, 46) deposited onto the support structure and electrically isolated from the first material, wherein the first material and the second material are selected to have a voltage potential difference when in contact with a conducting fluid to provide power to activate the device; a control module (38, 48) associated with the support structure and electrically connected to the first material and the second material to control conductance between the first material and the second material, wherein, when the first material and the second material are in contact with the conductive fluid, a change in conductance between the first material and the second material alters a current flow extending through the conductive fluid between the first material and the second material and thereby encode information in a current signature; a unit (12b, 75) configured to act as a secondary communication module and to be in communication with the control module and associated with the support structure to receive a signal from an external source; and a sealed housing defining a cavity, wherein the system is positioned within the cavity; characterized in that the device further comprises: a release material within the cavity, wherein the unit is configured to generate a release command upon the system receiving the signal from the external source, wherein the release command is configured to cause the release material to activate and expand via electroactive or chemical means and open the sealed housing to release the system into the conducting fluid to activate the partial power source and thereby activate the control module. a system (12a, 30, 40) comprising: a support structure (32, 42); a partial power source comprising: a first material (34, 44) deposited onto the support structure; and a second material (36, 46) deposited onto the support structure and electrically isolated from the first material, wherein the first material and the second material are selected to have a voltage potential difference when in contact with a conducting fluid to provide power to activate the device; a support structure (32, 42); a partial power source comprising: a first material (34, 44) deposited onto the support structure; and a second material (36, 46) deposited onto the support structure and electrically isolated from the first material, wherein the first material and the second material are selected to have a voltage potential difference when in contact with a conducting fluid to provide power to activate the device; a first material (34, 44) deposited onto the support structure; and a second material (36, 46) deposited onto the support structure and electrically isolated from the first material, wherein the first material and the second material are selected to have a voltage potential difference when in contact with a conducting fluid to provide power to activate the device; a control module (38, 48) associated with the support structure and electrically connected to the first material and the second material to control conductance between the first material and the second material, wherein, when the first material and the second material are in contact with the conductive fluid, a change in conductance between the first material and the second material alters a current flow extending through the conductive fluid between the first material and the second material and thereby encode information in a current signature; a unit (12b, 75) configured to act as a secondary communication module and to be in communication with the control module and associated with the support structure to receive a signal from an external source; and a sealed housing defining a cavity, wherein the system is positioned within the cavity; a release material within the cavity, wherein the unit is configured to generate a release command upon the system receiving the signal from the external source, wherein the release command is configured to cause the release material to activate and expand via electroactive or chemical means and open the sealed housing to release the system into the conducting fluid to activate the partial power source and thereby activate the control module.