Abstract: A liquid conductivity sensor which features simply and inexpensively driving the excitation transformer of a two-transformer/fluid-loop remote conductivity sensor with a square wave excitation signal provided by a digital timer and a flip-flop. Also disclosed is using an electrodeless conductivity sensor to sense conductivity of dialysate.

Abstract: Monitoring concentration of components of blood flowing through a flowpath including flowing the components through a transparent channel, directing light to the channel along an axis intersecting the channel, detecting light passing through the channel along the axis, detecting light scattered off of the axis, and determining concentration of components based on the light passing along the axis and/or the light scattered off of the axis. Also disclosed is a movable cover to block ambient light from a photodetector after mounting of a removable transparent flow channel.

Abstract: A pump control apparatus including a variable speed pump controllable in response to a pump drive signal, a signal generator generating a commanded flowrate signal indicating desired flowrate of the pump, a flowrate sensor providing a sensed flowrate signal indicating sensed flowrate of the pump, and an integrator connected to the sensor and generator to receive and integrate the commanded flowrate signal and the sensed flowrate signal and to provide the pump drive signal based on the difference in integrated values of the signals so as to achieve desired commanded volume over time.

Abstract: A system for supplying fluid for a fluid flow transfer device and achieving target ultrafiltration fluid losses by automatically, periodically monitoring the ultrafiltration rate and transmembrane pressure, computing the transmembrane pressure necessary to achieve the target fluid loss by the end of a session, and adjusting the transmembrane pressure to the computed value.