Apparatus comprising: a pressure sensor assembly comprising: a printed circuit board having a front side and a back side ; a pressure sensor having a front side and a back side, the pressure sensor mounted to the printed circuit board with the back side of the pressure sensor facing the front side of the printed circuit board ; and a force transmitting member having a front side and a back side , wherein the front side of the force transmitting member includes a cured silicone elastomer and the back side of the force transmitting member engages the front side of the pressure sensor, wherein the force transmitting member transmits a force applied to the front side of the force transmitting member to the front side of the pressure sensor ; the apparatus further comprising a reservoir including one or more extensions that define an opening , wherein the front side of the force transmitting member is exposed to the interior of the reservoir , and wherein the one or more extensions are configured to engage the front side of the force transmitting member to seal the opening characterised by a clip configured to secure the pressure sensor assembly within the opening of the reservoir , to apply a force on the printed circuit board of the pressure sensor assembly and to push the pressure sensor assembly against the one or more extensions . a pressure sensor assembly comprising: a printed circuit board having a front side and a back side ; a pressure sensor having a front side and a back side, the pressure sensor mounted to the printed circuit board with the back side of the pressure sensor facing the front side of the printed circuit board ; and a force transmitting member having a front side and a back side , wherein the front side of the force transmitting member includes a cured silicone elastomer and the back side of the force transmitting member engages the front side of the pressure sensor, wherein the force transmitting member transmits a force applied to the front side of the force transmitting member to the front side of the pressure sensor ; a printed circuit board having a front side and a back side ; a pressure sensor having a front side and a back side, the pressure sensor mounted to the printed circuit board with the back side of the pressure sensor facing the front side of the printed circuit board ; and a force transmitting member having a front side and a back side , wherein the front side of the force transmitting member includes a cured silicone elastomer and the back side of the force transmitting member engages the front side of the pressure sensor, wherein the force transmitting member transmits a force applied to the front side of the force transmitting member to the front side of the pressure sensor ; the apparatus further comprising a reservoir including one or more extensions that define an opening , wherein the front side of the force transmitting member is exposed to the interior of the reservoir , and wherein the one or more extensions are configured to engage the front side of the force transmitting member to seal the opening characterised by a clip configured to secure the pressure sensor assembly within the opening of the reservoir , to apply a force on the printed circuit board of the pressure sensor assembly and to push the pressure sensor assembly against the one or more extensions . <EOS>