A system for molecular analysis, comprising a fluidic channel configured to receive a sample comprising at least one molecule, wherein the fluidic channel includes a first electrode and a second electrode, wherein the first electrode is separated from the second electrode by a gap, which gap is dimensioned to permit the sample to pass through the gap; an electron source configured to emit electrons with a central kinetic energy and a kinetic energy distribution having a full width at half maximum (FWHM) of no greater than 1 electron Volt (eV), wherein the electron source is electrically coupled to the first electrode and comprises a thermal electron source and a quantum tunneling filter structure to filter the thermally distributed electrons by transmitting a majority of electrons having kinetic energies within a narrow range and filtering a majority of electrons having kinetic energies outside of this range; a current sensor electrically coupled to the second electrode and configured to detect electric current passing from the first electrode to the second electrode; and a controller coupled to the electron source and the current sensor, wherein the controller is configured to: (i) direct the electron source to emit the electrons to the first electrode and the gap upon flow of the sample through the gap, and (ii) use the current sensor to detect an electric current directed from the first electrode to the second electrode, wherein when the at least one molecule passes through the gap, an electric current flows from the first electrode to the second electrode and is detected by the current sensor, indicating a presence of the at least one molecule. a fluidic channel configured to receive a sample comprising at least one molecule, wherein the fluidic channel includes a first electrode and a second electrode, wherein the first electrode is separated from the second electrode by a gap, which gap is dimensioned to permit the sample to pass through the gap; an electron source configured to emit electrons with a central kinetic energy and a kinetic energy distribution having a full width at half maximum (FWHM) of no greater than 1 electron Volt (eV), wherein the electron source is electrically coupled to the first electrode and comprises a thermal electron source and a quantum tunneling filter structure to filter the thermally distributed electrons by transmitting a majority of electrons having kinetic energies within a narrow range and filtering a majority of electrons having kinetic energies outside of this range; a current sensor electrically coupled to the second electrode and configured to detect electric current passing from the first electrode to the second electrode; and a controller coupled to the electron source and the current sensor, wherein the controller is configured to: (i) direct the electron source to emit the electrons to the first electrode and the gap upon flow of the sample through the gap, and (ii) use the current sensor to detect an electric current directed from the first electrode to the second electrode, wherein when the at least one molecule passes through the gap, an electric current flows from the first electrode to the second electrode and is detected by the current sensor, indicating a presence of the at least one molecule. (i) direct the electron source to emit the electrons to the first electrode and the gap upon flow of the sample through the gap, and (ii) use the current sensor to detect an electric current directed from the first electrode to the second electrode, wherein when the at least one molecule passes through the gap, an electric current flows from the first electrode to the second electrode and is detected by the current sensor, indicating a presence of the at least one molecule.