Example devices include a cis well associated with a cis electrode, a trans well associated with a trans electrode, and a field effect transistor (FET) positioned between the cis well and the trans well. Examples of the field effect transistor (FET) include a fluidic system defined therein. The fluidic system includes a first cavity facing the cis well, a second cavity fluidically connected to the trans well, and a through via extending through the field effect transistor from the first cavity. A first nanoscale opening fluidically connects the cis well and the first cavity, the first nanoscale opening having an inner diameter. A second nanoscale opening fluidically connects the through via and the second cavity, the second nanoscale opening having an inner diameter. The second nanoscale opening inner diameter is larger than the first nanoscale opening inner diameter.