Treatment fluid devices methods and systems
A conductivity measurement device includes first and second conductivity measurement flow channels positioned in a fluid circuit and fluidly linked for fluid flow between the first and second conductivity measurement flow channels. A controller having a current source connected to the first and second conductivity channels applies alternating voltages at frequencies that are different, each being respective to one of the first and second conductivity cells.
1. A conductivity measurement device in a medicament generation system including a fluid circuit, the conductivity measurement device comprising:
a first conductivity measurement flow channel positioned in the fluid circuit;
a second conductivity measurement flow channel positioned in the fluid circuit;
an intermediate flow channel positioned in the fluid circuit and fluidly linking the first and second conductivity measurement flow channels to each other, the intermediate flow channel being at least partially bounded by a portion of a molded rigid case and a film adhered to the molded rigid case and being configured to maintain a constant content concentration of a fluid in a fluid flow from the first conductivity measurement flow channel to the second conductivity measurement flow channel; and
a controller having a current source connected to the first and second conductivity measurement flow channels, the controller being configured to apply alternating voltages at frequencies that are different, each frequency being respective to one of the first and second conductivity measurement flow channels.
2. The device of claim 1 , wherein the controller is configured to measure a first voltage drop across the first conductivity measurement flow channel, and
to measure a second voltage drop across the second conductivity measurement flow channel.
3. The device of claim 2 , wherein
the first conductivity measurement flow channel includes a first electrode and a second electrode,
one of the alternating voltages is applied to one of the first electrode and the second electrode, and
the first voltage drop is measured from the second electrode to the first electrode.
4. The device of claim 3 , wherein
the second conductivity measurement flow channel includes a third electrode and a fourth electrode,
another one of the alternating voltages is applied to one of the third electrode and the fourth electrode,
the second voltage drop is measured from the fourth electrode to the third electrode.
5. The device of claim 1 , wherein the respective frequency applied to the first conductivity measurement flow channel is selected to prevent interference in measurement of voltage drop with the respective frequency applied to the second conductivity measurement flow channel.
6. The device of claim 1 , wherein
the controller is configured to measure voltage drops across respective channels of the first and second conductivity measurement flow channels, and
the controller is configured to demodulate the voltage drops by low-pass-filtering the voltage drops.
7. The device of claim 6 , wherein
a cutoff frequency of a filter used by the controller for the low-pass filtering is at least the respective frequency applied to the second conductivity measurement flow channel.
8. The device of claim 1 , wherein
the first conductivity measurement flow channel has a first orientation that provides a first fluid pathway for the fluid to flow in a first direction, and
the second conductivity measurement flow channel has a second orientation that provides a second fluid pathway for said fluid that has passed through the first conductivity measurement flow channel to flow in a second direction, different than the first direction, while flowing through the second conductivity measurement flow channel.
9. The device of claim 1 , wherein the respective frequency applied to the first conductivity measurement flow channel is between 1.2 and 5 times the respective frequency applied to the second conductivity measurement flow channel.
10. A medicament delivery system, comprising:
a fluid circuit attached to a pump and a controller;
the fluid circuit having:
a first conductivity measurement portion and a second conductivity measurement portion adjacent to the first conductivity measurement portion,
a first intermediate portion linking the first and second conductivity measurement portions to each other,
a third conductivity measurement portion and a fourth conductivity measurement portion adjacent to the third conductivity measurement portion,
a second intermediate portion linking the third and fourth conductivity measurement portions to each other,
a flow channel linking the second and third conductivity measurement portions to each other, and
a medicament concentration line connected to the flow channel at a location between the second and third conductivity measurement portions;
the first, second, third, and fourth conductivity measurement portions each having a pair of electrodes;
the first intermediate portion being configured to maintain a constant content concentration of a fluid in a fluid flow from the first conductivity measurement portion to the second conductivity measurement portion;
the second intermediate portion being configured to maintain a constant content concentration of the fluid in a fluid flow from the third conductivity measurement portion to the fourth conductivity measurement portion; and
the controller being connected to the pairs of electrodes and configured to generate a current between each pair of the electrodes cyclically at different times so the current exists between only the pair of electrodes of one of the first, second, third, and fourth conductivity measurement portions at a given time.
11. The system of claim 10 , wherein the current is an alternating current.
12. The system of claim 10 , wherein the current between each pair of electrodes is maintained for only a fraction of a second.
13. The system of claim 10 , wherein the controller is further configured to measure respective voltage drops across the first, second, third, and fourth conductivity measurement portions.
14. The system of claim 13 , wherein the controller is further configured to demodulate the respective voltage drops by low-pass-filtering the respective voltage drops.
15. The system of claim 10 , further comprising an accumulator disposed in the fluid circuit, upstream from the first, second, third, and fourth conductivity measurement portions.
16. A medicament delivery system, comprising:
a pump actuator adapted to receive a predefined fluid circuit and a controller;
the fluid circuit having:
a first conductivity measurement portion and a second conductivity measurement portion adjacent to the first conductivity measurement portion,
a first intermediate portion linking the first and second conductivity measurement portions to each other,
a third conductivity measurement portion and a fourth conductivity measurement portion adjacent to the third conductivity measurement portion,
a second intermediate portion linking the third and fourth conductivity measurement portions to each other,
a flow channel linking the second and third conductivity measurement portions to each other, and
a medicament concentration line connected to the flow channel at a location between the second and third conductivity measurement portions;
the first, second, third, and fourth conductivity measurement portions each having a pair of electrodes;
the first intermediate portion being configured to maintain a constant content concentration of a fluid in a fluid flow from the first conductivity measurement portion to the second conductivity measurement portion;
the second intermediate portion being configured to maintain a constant content concentration of the fluid in a fluid flow from the third conductivity measurement portion to the fourth conductivity measurement portion; and
the controller being connectable to the pairs of electrodes and configured to generate a current between each pair of electrodes cyclically at different times so the current exists between only one of the pairs of electrodes at a given time.
17. The system of claim 16 , wherein the current is an alternating current.
18. The system of claim 16 , wherein the current between each pair of electrodes is maintained for only a fraction of a second.
19. The system of claim 16 , wherein the controller is further configured to measure respective voltage drops across the first, second, third, and fourth conductivity measurement portions.
20. The system of claim 16 , further comprising an accumulator disposed in the fluid circuit, upstream from the first, second, third, and fourth conductivity measurement portions.