A device for monitoring analyte levels, comprising: an in vivo analyte sensor (101, 210, 1210) for transcutaneous positioning in fluid contact with interstitial fluid of a subject, and configured to generate current when in contact with interstitial fluid; and sensor electronics comprising: a capacitor device, a switch positioned between the in vivo analyte sensor (101, 210, 1210) and the capacitor device, and one or more components, wherein: the capacitor device is configured to receive the current through the switch to accumulate charge, wherein the switch has a first state and a second state, wherein the capacitor device is operably coupled to the in vivo analyte sensor (101, 210, 1210) when the switch is in the first state such that the capacitor device is able to receive the current, and wherein the capacitor device is operably decoupled from the in vivo analyte sensor (101, 210, 1210) when the switch is in the second state such that the capacitor device is unable to receive the current; the switch is configured to switch from the first state to the second state upon detecting a first magnetic field that exceeds a threshold level; the capacitor device is configured to discharge, when the switch is in the second state, accumulated charge to power the one or more components, wherein a first component of the one or more components is configured to generate a second magnetic field indicative that the switch is in the second state by using the accumulated charge discharged from the capacitor device; the in vivo analyte sensor (101, 210, 1210) is a self-powered analyte sensor; and the current that the in vivo analyte sensor is configured to generate is proportional to an analyte concentration in the interstitial fluid. an in vivo analyte sensor (101, 210, 1210) for transcutaneous positioning in fluid contact with interstitial fluid of a subject, and configured to generate current when in contact with interstitial fluid; and sensor electronics comprising: a capacitor device, a switch positioned between the in vivo analyte sensor (101, 210, 1210) and the capacitor device, and one or more components, wherein: the capacitor device is configured to receive the current through the switch to accumulate charge, wherein the switch has a first state and a second state, wherein the capacitor device is operably coupled to the in vivo analyte sensor (101, 210, 1210) when the switch is in the first state such that the capacitor device is able to receive the current, and wherein the capacitor device is operably decoupled from the in vivo analyte sensor (101, 210, 1210) when the switch is in the second state such that the capacitor device is unable to receive the current; the switch is configured to switch from the first state to the second state upon detecting a first magnetic field that exceeds a threshold level; the capacitor device is configured to discharge, when the switch is in the second state, accumulated charge to power the one or more components, wherein a first component of the one or more components is configured to generate a second magnetic field indicative that the switch is in the second state by using the accumulated charge discharged from the capacitor device; the in vivo analyte sensor (101, 210, 1210) is a self-powered analyte sensor; and the current that the in vivo analyte sensor is configured to generate is proportional to an analyte concentration in the interstitial fluid. the capacitor device is configured to receive the current through the switch to accumulate charge, wherein the switch has a first state and a second state, wherein the capacitor device is operably coupled to the in vivo analyte sensor (101, 210, 1210) when the switch is in the first state such that the capacitor device is able to receive the current, and wherein the capacitor device is operably decoupled from the in vivo analyte sensor (101, 210, 1210) when the switch is in the second state such that the capacitor device is unable to receive the current; the switch is configured to switch from the first state to the second state upon detecting a first magnetic field that exceeds a threshold level; the capacitor device is configured to discharge, when the switch is in the second state, accumulated charge to power the one or more components, wherein a first component of the one or more components is configured to generate a second magnetic field indicative that the switch is in the second state by using the accumulated charge discharged from the capacitor device; the in vivo analyte sensor (101, 210, 1210) is a self-powered analyte sensor; and the current that the in vivo analyte sensor is configured to generate is proportional to an analyte concentration in the interstitial fluid.