Flow Rate Accuracy of a Fluidic Delivery System

• US 20120150356A1
• Filed: 02/18/2012
• Published: 06/14/2012
• Est. Priority Date: 10/26/2005
• Status: Active Grant

• Current Assignee: Medos International Sarl (Johnson & Johnson)
• Original Assignee: Codman Neuro Sciences Sarl (Johnson & Johnson)
• Inventors: Crivelli, Rocco, Ginggen, Alec, Bork, Toralf
• Granted Patent: US 8,740,182 B2
• Time in Patent Office: Days
• US Class Current: 700/282
• CPC Class Codes: A61M 2205/0294 Piezoelectric materials
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 2205/702 automatically during use
• CPC Class Codes: A61M 2205/8212 with means or measures taken for minimising energy consumption
• CPC Class Codes: A61M 39/22 Valves or arrangement of valves A61M39/02, A61M39/0247, A61M39/16 take precedence; regulating valves in infusion systems A61M5/16881; in devices worn by the patient for the reception of urine, faeces, catamenial or other discharge, or in colostomy devices A61F5/4405
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/16881 Regulating valves on-off valves, e.g. clamps A61M39/28
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: F16K 1/34 Cutting-off parts, e.g. valve members, seats F16K1/06, F16K1/12, F16K1/14, F16K1/26 take precedence
• CPC Class Codes: F16K 31/006 having a free end
• CPC Class Codes: H10N 30/802 Circuitry or processes for operating piezoelectric or electrostrictive devices not otherwise provided for, e.g. drive circuits
• CPC Class Codes: Y10T 137/86389 Programmer or timer

Abstract

Improving the accuracy of the flow rate of a valve in a fiuidic delivery device in which a desired flow rate may be achieved by varying the duty cycle of the valve. The flow rate of fluid delivery from the valve over its lifetime is stabilized by minimizing the voltage OPENING time of the valve to account for valve and piezoelectric actuator drift. Also, the valve OPENING time of one or more fiuidic parameters that impact on the flow rate delivery by the valve and differ among fiuidic delivery devices is compensated to optimize the flow rate accuracy.

Claims

1. A method for optimizing flow rate accuracy of a fluidic delivery system by compensating for at least one fluidic parameter effecting the flow rate accuracy of fluid dispensed by a valve, a block representing a predetermined duration of time over which the valve opens once and closes once, the valve being associated with a fluidic delivery device including a first fluidic delivery device processor and a first non-volatile memory device having stored therein at least one calibrated fluidic parameter determined for the fluidic delivery device, the fluidic delivery device being programmable by a control device having a control device processor, the method comprising the steps of:

(a) calculating using the control device processor an Integer Compensated Valve OPENING Time Per Block and a Remainder Compensated Valve Opening Time Per Predetermined Time Interval based on the at least one calibrated fluidic parameter retrieved from the first non-volatile memory device;

(b) transmitting from the control device to the fluidic delivery device the calculated Integer Compensated Valve OPENING Time Per Block and the Remainder Compensated Valve Opening Time Per Predetermined Time Interval;

(c) distributing the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval as uniformly as possible to those blocks in the predetermined time interval;

(d) determining for each block per predetermined time interval a Total Compensated Valve OPENING Time by adding the Integer Compensated Valve OPENING Time Per Block and, if distributed to that particular block in the predetermined time interval, the uniformly as possible distributed Remainder Compensated Valve OPENING Time Per Predetermined Time Interval; and

(e) optimizing the flow rate accuracy of the fluidic delivery device by opening the valve based on the Total Compensated Valve OPENING time which has compensated for the fluidic parameters.

2. The method in accordance with claim 1, wherein the at least one calibrated fluidic parameter for the fluidic delivery device is stored in the first non-volatile memory device at a time of manufacture of the fluidic delivery device.

3. The method in accordance with claim. 1, wherein-the at least one calibrated fluidic parameters comprises at least one of compliance effect, maximum flow rate, temperature-pressure relationship of reservoir fluid, valve OPENING time, and valve CLOSING time.

4. The method in accordance with claim 1, wherein the Integer Compensated Valve OPENING Time Per Block is determined as:

Integer Compensated Valve OPENING Time Per Block=Integer (Maximum Flow Rate Compensation Component+Valve OPENING Time Compensation Component+Valve CLOSING Time Compensation Component+Compliance Effect Compensation Component+Temperature-Pressure Relationship Compensation Component).

5. The method in accordance with claim 4, wherein the Maximum Flow Rate Compensation Component is determined as:

Maximum Flow Rate Compensation Component=(programmed flow rate/calibrated maximum flow rate)*Duration of Block

wherein,

the programmed flow rate is programmed by the user;

the calibrated maximum flow rate is calibrated at a time of manufacture of the fluidic delivery; and

the Duration of Block is a duration of time for the block in which the valve is opened once and closed once.

6. The method in accordance with claim 5, wherein the Remainder Compensated Valve Opening Time Per Predetermined Time Interval is determined as:

Remainder Compensated Valve OPENING Time Per Predetermined Time Interval=MOD ((((Maximum Flow Rate Compensation Component)*Duration of the Block*Number of Blocks in the predetermined time interval)+(Valve OPENING Time Compensation Component*Number of Blocks in the predetermined time interval )+(Valve CLOSING Time Compensation Component*Number of Blocks in the predetermined time interval)+(Temperature-Pressure Relationship Compensation Component*Number of Blocks in the predetermined time interval)), Number of Blocks in the predetermined time interval).

7. The method in accordance with claim 1, wherein step (c) comprises the steps of:

if the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval is a whole number equally divisible among the total number of blocks in the predetermined time interval without a remainder, diving the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval by the number of blocks per predetermined time interval and distributing equally to each block; and

if the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval is a whole number that is not equally divisible among the total number of blocks in the predetermined time interval without a remainder, distributing as uniformly as possible as a whole number of one or more seconds among less than all the blocks within the predetermined time interval.

8. The method in accordance with claim 1, wherein in step (a) the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval are calculated by the control device processor twice to verify the consistency of the data prior to being transmitted to the fluidic delivery device.

9. The method in accordance with claim 8, wherein verification of the consistency of the data comprises the steps of performing a first calculation of the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval using a first portion of the programming source code for the control device processor, and performing a second calculation of the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval using a second portion of the programming source code of the control device processor, different than the first portion.

10. The method in accordance with claim 1, wherein the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval are stored in a second non-volatile memory device associated with the fluidic delivery device.

11. The method in accordance with claim 10, wherein the first non-volatile memory device is a FLASH memory and the second non-volatile memory device is an EEPROM.

12. The method in accordance with claim 11, further comprising the step of checking for corruption of the at least one calibrated fluidic parameters stored in the FLASH memory by calculating a FLASH code memory CRC and comparing this calculated value with a FLASH code memory CRC previously stored in the FLASH memory at the time of manufacture of the fluidic delivery device.

13. The method in accordance with claim 12, wherein the checking of the FLASH memory occurs during self-testing of the fluidic delivery device.

14. The method in accordance with claim 11, wherein the first fluidic delivery device processor has an associated RAM, the method further comprising the steps of:

copying entire contents of the EEPROM to the RAM; and

calculating the EEPROM checksum and verifying the calculated value with a previously stored checksum in the EEPROM.

15. The method in accordance with claim 11, wherein the fluidic delivery device has at least one additional processor, each of the at least one additional processors having an associated FLASH memory and an associated RAM, the method further comprising the steps of:

storing drug delivery profile data received from the control device in the EEPROM;

during reset of any of the processors, copying drug delivery profile data stored in the EEPROM to the respective associated RAMs of each of the processors; and

during self-testing of the fluidic delivery device detecting any discrepancy between the drug profile data stored in EEPROM and that stored in any of the RAMs in the associated processors.

34. The method in accordance with claim 1, wherein the predetermined time interval is one hour.

16. A fluidic delivery system with optimized flow rate accuracy by compensating for at least one fluidic parameter effecting the flow rate accuracy of fluid dispensed by a valve, a block representing a predetermined duration of time over which the valve opens once and closes once, comprising:

a control device having a control device processor; and

a fluidic delivery device including the valve, a first fluidic delivery device processor and a first non-volatile memory device for storing the flow rate and at least one calibrated fluidic parameter associated with the fluidic delivery device;

the fluidic delivery device being programmed by the control device;

the control device processor being programmed to;

(a) calculate using the control device processor an Integer Compensated Valve OPENING Time Per Block and a I Remainder Compensated Valve Opening Time Per Predetermined Time Interval based on the at least one calibrated fluidic parameter retrieved from the first non-volatile memory device;

(b) transmit from the control device to the fluidic delivery device the calculated Integer Compensated Valve OPENING Time Per Block and the Remainder Compensated Valve Opening Time Per Predetermined Time Interval;

the first fluidic delivery device processor being programmed to;

(c) distribute the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval as uniformly as possible to those blocks in the predetermined time interval;

(d) determine for each block per the predetermined time interval a Total Compensated Valve OPENING Time by adding the Integer Compensated Valve OPENING Time Per Block and, if distributed to that particular block in the predetermined time interval, the uniformly as possible distributed Remainder Compensated Valve OPENING Time Per Predetermined Time Interval; and

(e) optimize the flow rate accuracy of the fluidic delivery device by opening the valve based on the Total Compensated Valve OPENING time which has compensated for the fluidic parameters.

17. The system in accordance with claim 16, wherein the at least one calibrated fluidic parameter for the fluidic delivery device is stored in the first non-volatile memory device at a time of manufacture of the fluidic delivery device.

18. The system in accordance with claim 16, wherein the at least one calibrated fluidic parameters comprises at least one of compliance effect, maximum flow rate, temperature-pressure relationship of reservoir fluid, valve OPENING time, and valve CLOSING time.

19. The system in accordance with claim 16, wherein the programming of the first fluidic delivery device processor to calculate the Integer Compensated Valve OPENING Time Per Block is determined as:

Integer Compensated Valve OPENING Time Per Block=Integer (Maximum Flow Rate Compensation Component+Valve OPENING Time Compensation Component+Valve CLOSING Time Compensation Component+Compliance Effect Compensation Component+Temperature-Pressure Relationship Compensation Component).

20. The system in accordance with claim 19, wherein the programming of the first fluidic delivery device processor to calculate the Maximum Flow Rate Compensation Component is determined as:

Maximum Flow Rate Compensation Component=(programmed flow rate/calibrated maximum flow rate)*Duration of Block

wherein,

the programmed flow rate is programmed by the user;

the calibrated maximum flow rate is calibrated at a time of manufacture of the fluidic delivery; and

the Duration of Block is a duration of time for the block in which the valve is opened once and closed once.

21. The system in accordance with claim 20, wherein the programming of the first fluidic delivery device processor to calculate the Remainder Compensated Valve Opening Time Per Predetermined Time Interval is determined as:

Remainder Compensated Valve OPENING Time Per Predetermined Time Interval=MOD ((((Maximum Flow Rate Compensation Component)*Duration of the Block*Number of Blocks in the predetermined time interval)+(Valve OPENING Time Compensation Component*Number of Blocks in the predetermined time interval)+(Valve CLOSING Time Compensation Component*Number of Blocks in the predetermined time interval)+(Temperature-Pressure Relationship Compensation Component*Number of Blocks in the predetermined time interval)), Number of Blocks in the predetermined time interval)

22. The system in accordance with claim 16, wherein the programming of the fluidic delivery device processor to distribute the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval comprises the functions of:

if the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval is a whole number equally divisible among the total number of blocks in the predetermined time interval without a remainder, dividing the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval by the number of blocks per the predetermined time interval and distributing equally to each block; and

if the Remainder Compensated Valve OPENING Time Per Predetermined Time Interval is a whole number that is not equally divisible among the total number of blocks in the predetermined time interval without a remainder, distributing as uniformly as possible as a whole number of one or more seconds among less than all the blocks within the predetermined time interval.

23. The system in accordance with claim 16, wherein me programming of the control device processor to calculate the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval are calculated by the control device processor twice to verify the consistency of the data prior to being transmitted to the fluidic delivery device.

24. The system in accordance with claim 23, wherein the consistency of the calculated Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval is verified by performing a first calculation of the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval using a first portion of the programming source code for the control device processor, and performing a second calculation of the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval using a second portion of the programming source code of the control device processor, different than the first portion.

25. The system in accordance with claim 16, wherein the Integer Compensated Valve OPENING Time Per Block and Remainder Compensated Valve OPENING Time Per Predetermined Time Interval are stored in a second non-volatile memory associated with the fluidic delivery device.

26. The system in accordance with claim 25, wherein the first non-volatile memory device is a FLASH memory and the second non-volatile memory device is an EEPROM.

27. The system in accordance with claim 26, wherein the first fluidic delivery device processor is programmed to check for corruption of the at least one calibrated fluidic parameters stored in the FLASH memory by calculating a FLASH code memory CRC and comparing this calculated value with a FLASH code memory CRC previously stored in the FLASH memory at the time of manufacture of the fluidic delivery device.

28. The system in accordance with claim 27, wherein the checking of the FLASH memory occurs during self-testing of the fluidic delivery device.

29. The system in accordance with claim 26, wherein the first fluidic delivery processor has an associated RAM, the first fluidic delivery device processor is programmed to:

copy entire contents of the EEPROM to the RAM;

calculate the EEPROM checksum; and

verify the calculated EEPROM checksum with a previously stored checksum in the EEPROM.

30. The system in accordance with claim 26, wherein the fluidic delivery device has at least one additional processor, each of the at least one additional processors having an associated FLASH memory and an associated RAM;

wherein the EEPROM stores drug delivery profile data received from the control device; and

wherein the first fluidic delivery processor is programmed to;

copy drug delivery profile data stored in the EEPROM to the respective associated RAMs of each of the processors, during reset of any of the processors; and

detect any discrepancy between the drug profile data stored in EEPROM and that stored in any of the RAMs in the associated processors, during self-testing of the fluidic delivery device.

35. The system in accordance with claim 16, wherein the predetermined time interval is one hour.

31. A valve assembly, comprising:

a power supply;

charge pump circuitry powered by the power supply;

a piezoelectric actuator charged by the charge pump circuitry, the charge applied across the piezoelectric actuator reaching a predetermined opening voltage threshold over a predetermined opening voltage rise time; and

a valve transitioning from a CLOSED state to an OPENED state when the piezoelectric actuator exceeds the predetermined opening voltage threshold, a block representing a predetermined duration of time over which the valve opens once and closes once;

the piezoelectric actuator consuming energy from the power supply only during the predetermined opening voltage rise time while the piezoelectric actuator is charging prior to reaching the predetermined threshold voltage, wherein the predetermined rise time is less than the block.

32. The valve assembly iii accordance with claim 31, wherein the predetermined threshold voltage is approximately 60 V.

33. The valve assembly in accordance with claim 31, further comprising at least one relatively low leakage diode electrically connected to the piezoelectric actuator to retain the charge applied to the piezoelectric actuator with minimal leakage.