Densitometer of the present invention includes a housing having a recess, emitting surface that emits the electrodes housed in said recess, the measurement surface in contact with the measurement object, the measurement object which has entered from the measuring surface in a recess above, and said it has been opened to the measuring surface and the emission surface has a plurality of holes for the measurement target enters a permeable membrane which seals the depressions above, are encapsulated in the recess, the electrode an internal solution in contact with the with the permeable membrane and, as the opening area of the hole of at least said measurement surface is increased or decreased reversibly, the adjuster applying mechanical loading to said permeable membrane, said adjustment unit It is connected, comprising a control unit for controlling the presence or absence of mechanical loading to make the change in the intensity of the mechanical load applied to the permeable membrane, or to the permeable membrane本発明の濃度計は、くぼみを有するハウジングと、前記くぼみの中に収容された電極と、測定対象に接触する測定面、前記測定面から侵入した測定対象を前記くぼみ内に放出する放出面、および前記測定面および前記放出面に開口しており、前記測定対象が進入するための複数の孔を有し、前記くぼみを封止する浸透膜と、前記くぼみの中に封入されて、前記電極と前記浸透膜とに接触する内部液と、少なくとも前記測定面の前記孔の開口面積が可逆的に増加または減少するように、前記浸透膜に機械的負荷を加える調整部と、前記調整部に接続されて、前記浸透膜に加える機械的負荷の強弱の変化、または前記浸透膜に加える機械的負荷の有無、を制御する制御部と、を含む。
