Resistor pulse modulation

• US 20080106238A1
• Filed: 09/19/2007
• Published: 05/08/2008
• Est. Priority Date: 09/21/2006
• Status: Active Grant

• Current Assignee: Bio-Rad Laboratories Incorporated
• Original Assignee: Bio-Rad Laboratories Incorporated
• Inventors: Ragsdale, Charles
• Granted Patent: US 7,750,605 B2
• Time in Patent Office: Days
• US Class Current: 320/166
• CPC Class Codes: A61N 1/327 for enhancing the absorption properties of tissue, e.g. by electroporation
• CPC Class Codes: C12M 35/02 Electrical or electromagnetic means, e.g. for electroporation or for cell fusion
• CPC Class Codes: C12N 13/00 Treatment of microorganisms or enzymes with electrical or wave energy, e.g. magnetism, sonic waves
• CPC Class Codes: H03K 3/53 by the use of an energy-accumulating element discharged through the load by a switching device controlled by an external signal and not incorporating positive feedback H03K3/335 takes precedence

Abstract

Systems, methods, apparatus, and circuits for controlling an electrical signal transmitted to a sample load are provided. The electrical signal produced by a capacitor is controlled via a control signal sent to a variable resistance device that is connected in parallel with the sample load. The variable resistance device includes a resistance and a switch in series. The control signal opens and closes the switch, thus providing a variable resistance based on the amount of time the switch is closed.

Claims

1. A method of controlling an electrical signal transmitted to a sample load, comprising:

charging a capacitance;

connecting the capacitance with the sample load and a variable resistance device connected in parallel with the sample load, the variable resistance device including;

a first resistor;

a first switch connected in series with the first resistor, wherein the first switch is opened and closed by a first control signal;

transmitting an electrical signal from the capacitance to the sample load and the variable resistance device; and

controlling the electrical signal with the first control signal.

2. The method of claim 1, wherein the first control signal opens and closes the first switch such that the variable resistance device has a constant resistance while the electrical signal is transmitted.

3. The method of claim 2, wherein the constant resistance is specified by a user.

4. The method of claim 1, wherein the first control signal is a pulse width modulated signal.

5. The method of claim 1, wherein the first control signal opens and closes the first switch such that the resistance of the variable resistance device varies while the electrical signal is transmitted.

6. The method of claim 5, wherein the first control signal is a pulse width modulated signal, and wherein the pulse widths change as to vary the resistance of the variable resistance device while the electrical signal is transmitted.

7. The method of claim 1, wherein the electrical signal is an exponentially decaying pulse and the control signal determines a time constant τ

for the exponential decay.

8. The method of claim 1, wherein the electrical signal is a square wave.

9. The method of claim 1, wherein the variable resistance device further includes one or more other resistors in series with the first resistor.

10. The method of claim 1, wherein the variable resistance device further includes:

a second resistor connected in parallel with the first resistor; and

a second switch connected in series with the second resistor, wherein the second switch is opened and closed by the first control signal.

11. The method of claim 10, wherein the variable resistance device further includes:

one or more additional resistors, each connected in parallel with the first and second resistors and with the other additional resistors; and

one or more additional switches, each connected in series with one of the additional resistors.

12. The method of claim 1, wherein the sample load contains biological molecules that are electroporated by the electrical signal.

13. A circuit configured to provide a controllable electrical signal to a sample load, comprising:

a capacitance selectively connected with the sample load; and

a variable resistance device connected in parallel with the sample load, the variable resistance device including;

a first resistor; and

a first switch in series with the first resistor, wherein the first switch is opened and closed by a first control signal;

wherein when the capacitance is charged and selected to be connected with the sample load, an electrical signal is transmitted from the capacitance to the sample load and the variable resistance device, and wherein the electrical signal is controlled with the first control signal.

14. The circuit of claim 13, wherein the capacitance is connected in parallel with sample load.

15. The circuit of claim 13, wherein the first control signal is a pulse width modulated signal.

16. The circuit of claim 13, wherein the first control signal opens and closes the first switch such that the resistance of the variable resistance device varies while the electrical signal is transmitted.

17. The circuit of claim 13, wherein the first control signal is a pulse width modulated signal, and wherein the pulse widths change as to vary the resistance of the variable resistance device while the electrical signal is transmitted.

18. The circuit of claim 13, wherein the electrical signal is an exponentially decaying pulse and the control signal determines a time constant τ

for the exponential decay.

19. The circuit of claim 13, wherein the variable resistance device further includes one or more other resistors in series with the first resistor.

20. The circuit of claim 13, wherein the variable resistance device further includes:

a second resistor connected in parallel with the first resistor; and

a second switch connected in series with the second resistor, wherein the second switch is opened and closed by the first control signal.

21. The circuit of claim 20, wherein the variable resistance device further includes:

one or more additional resistors, each connected in parallel with the first and second resistors and with the other additional resistors; and

one or more additional switches, each connected in series with one of the additional resistors.

22. An electroporator system for providing a controllable electrical signal to a sample load, comprising:

a capacitance selectively connected with the sample load; and

a variable resistance device connected in parallel with the sample load, the variable resistance device including;

a first resistor; and

a first switch in series with the first resistor, wherein the first switch is opened and closed by a first control signal;

wherein when the capacitance is charged and selected to be connected with the sample load, an electrical signal is transmitted from the capacitance to the sample load and the variable resistance device, and wherein the electrical signal is controlled with the first control signal.

23. The electroporator system of claim 22, further comprising a charging circuit that charges the capacitance to a specified voltage.

24. The electroporator system of claim 22, further comprising a switching driver that provides the first control signal that determines the resistance of the variable resistance device by opening and closing the first switch.

25. The electroporator system of claim 24, further comprising a high voltage driver for selectively connecting the capacitance to the sample load.