In one embodiment, an apparatus includes a sensor and a controller having a processor and a memory. The memory includes logic operable, when executed by the processor, to connect each electrode of a first subset of electrodes of the sensor and determine a first value associated with the first subset of electrodes. Based at least on the first value, the logic is further operable to alter the first subset of electrodes to a second subset of electrodes and connect, in response to determining to alter the first subset of electrodes to the second subset of electrodes, each electrode of the second subset of electrodes of the sensor.