Initialization of a dosing unit for drug infusion

1. Method for initializing a dosing unit of an ambulatory infusion system, the method including carrying out a first priming routine, the first priming routine including:

providing the dosing unit with a dosing chamber of the dosing unit having a minimal dosing chamber volume, a draining valve of the dosing unit being closed and a filling valve of the dosing unit being open;

measuring an initial reservoir fluid pressure p 2 and computing, based on the initial reservoir fluid pressure p 2 , a first priming volume v 1 , with a liquid drug reservoir being fluidically coupled with the dosing chamber via a reservoir coupling conduit and the opened filling valve;

increasing the dosing chamber volume by the first priming volume v 1 , with the first priming volume v 1 being computed such that the reservoir coupling conduit is filled with liquid drug substantially completely at the end of the dosing chamber volume increasing;

closing the filling valve and opening the draining valve;

emptying the dosing unit by decreasing the dosing chamber volume to the minimal dosing chamber volume.

2. Method according to claim 1 , wherein the method further includes, prior to carrying out the first priming routine, carrying out a sensor calibration routine, the sensor calibration routine including:

providing the dosing unit in an initial state with the dosing chamber being gas-filled and both of the filling valve and the draining valve being closed, resulting in the dosing chamber being fluidic isolated;

decreasing the dosing chamber volume, thereby compressing the gas inside the dosing unit to a compression factor c 1 ;

reading, at the compression factor c 1 , an output value p 1 * of a pressure sensor in fluidic coupling with the dosing chamber and computing, based on the output value p 1 * and the compression factor c, a pressure sensor calibration, and storing the computed calibration;

opening the draining valve with the filling valve staying closed; and

emptying the dosing unit by further decreasing the dosing chamber volume to the minimal dosing chamber volume.

3. Method according to claim 1 , wherein the method further includes, following carrying out the first priming routine, carrying out a second priming routine, the second priming routine including:

closing the draining valve and opening the filling valve;

increasing the dosing chamber volume by a second priming volume;

closing the filling valve with the draining valve staying closed, resulting in the dosing chamber being fluidic isolated;

varying the dosing chamber volume and monitoring, during the variation, a dosing chamber pressure p C , and stopping the variation upon the dosing chamber pressure p C equalling a reference pressure; and

computing, based on an amount of variation of the dosing chamber volume, an air volume V air of air inside the dosing chamber.

4. Method according to claim 3 , wherein the second priming routine includes: the comparing the air volume V air with a pre-set threshold air volume V air,threshold and providing an alert if the air volume V air exceeds the pre-set threshold air volume V air,threshold .

5. Method according to claim 3 , wherein the second priming routine includes: taking into account a mechanical compliance of limiting walls of the dosing chamber for computing the air volume V air .

6. Method according to claim 1 , wherein the minimal dosing chamber volume is negligible or zero.

7. Method according to claim 1 , wherein the first priming routine includes: computing the first priming volume v 1 as

v

1

=

V

0

·

p

ref

p

ref

+

p

2

+

V

S

,

with V 0 being the fluidic volume of the reservoir coupling conduit, P ref being a reference pressure, and V s being a safety margin volume.

8. Method according to claim 1 , wherein increasing of the dosing chamber volume is achieved by displacing a piston of the dosing unit into a distal direction, and wherein decreasing of the dosing chamber volume is achieved by displacing the piston into an opposite proximal direction, with the piston being received in a dosing cylinder of the dosing unit and the dosing cylinder extending along a piston displacement axis, thus forming a movable limiting wall of the dosing chamber.

9. Method according to claim 1 , wherein opening and closing of the filling valve and the draining valve between an open and a closed state includes rotating a common shutoff body of the dosing unit.

10. Control unit, the control unit being designed for controlling operation of a dosing unit of an ambulatory infusion system, the control unit including a dosing chamber volume controller, a valve controller and a pressure sensor interface, the control unit being further designed for controlling execution of an initialization routine, the initialization routine including a first priming routine, the first priming routine causes the control unit to:

provide a dosing chamber of the dosing unit with a minimal dosing chamber volume, a draining valve of the dosing unit and open a filling valve of the dosing unit;

measure an initial reservoir fluid pressure p 2 and compute, based on the initial reservoir fluid pressure p 2 , a first priming volume v 1 , with the liquid drug reservoir being fluidically coupled with the dosing chamber via a reservoir coupling conduit and the opened filling valve;

increase the dosing chamber volume by the first priming volume v 1 , with the first priming volume v 1 being computed such that the reservoir coupling conduit is filled with liquid drug substantially completely at the end of the increase in the dosing chamber volume;

close the filling valve and open the draining valve; and

empty the dosing unit by a decrease in the dosing chamber volume to the minimal dosing chamber volume.

11. Control unit according to claim 10 , the control unit being further designed for controlling, prior to controlling execution of the first priming routine, execution of a sensor calibration routine, the sensor calibration routine causes the control unit to:

close the filling valve and the draining valve, which results in the dosing chamber being fluidic isolated;

decrease the dosing chamber volume, thereby compressing gas inside the dosing unit to a compression factor c 1 ;

read, at the compression factor c 1 , an output value p 1 * of a pressure sensor in fluidic coupling with the dosing chamber and compute, based on the output value p 1 * and the compression factor c, a pressure sensor calibration, and store the computed calibration;

open the draining valve with the filling valve staying closed; and

empty the dosing unit by a further decrease in the dosing chamber volume to the minimal dosing chamber volume.

12. Control unit according to claim 10 , the control unit being further designed for controlling, following execution of the first priming routine, execution of a second priming, the second priming causes the control unit to:

close the draining valve and open the filling valve;

increase the dosing chamber volume by a second priming volume v 2 ;

close the filling valve with the draining valve staying closed, which results in the dosing chamber to be fluidic isolated;

vary the dosing chamber volume and monitor, during the variation, a chamber pressure p C inside the dosing chamber, and stop the variation upon the chamber pressure p C equalling a reference pressure p ref ; and

compute, based on an amount of variation of the dosing chamber volume, an air volume v air of air inside the dosing chamber.

13. Control unit according to claim 10 , wherein the dosing chamber volume controller is designed for controlling a dosing chamber actuator to alternatively increase or decrease the dosing chamber volume continuously or in incremental steps.

14. Control unit according to claim 10 , wherein the valve controller is designed for controlling a rotary valve motor as a valve actuator and the dosing chamber volume controller is designed for controlling a rotary dosing chamber motor as a dosing chamber actuator.

15. Ambulatory infusion device, including:

a control unit according to claim 10 ;

a valve actuator, the valve actuator being operatively coupled to the valve controller and being designed for engaging a valve actuator coupler of a dosing unit;

a dosing chamber actuator, the dosing chamber actuator being operatively coupled to the dosing chamber actuator controller and being designed for engaging a movable limiting wall of the dosing chamber;

a casing, the casing enclosing the control unit, the valve actuator and the dosing chamber actuator; and

a dosing unit interface, the dosing unit interface being designed for releasably coupling the ambulatory infusion device with the dosing unit such that the valve actuator releasably engages a valve actuator coupler of a dosing unit.