Multi-channel electrophysiologic signal data acquisition system on an integrated circuit

• US 20060173364A1
• Filed: 10/28/2005
• Published: 08/03/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Worcester Polytechnic Institute
• Original Assignee: Worcester Polytechnic Institute
• Inventors: McNeill, John A., Michalson, William R., Clancy, Edward A.
• Granted Patent: US 7,896,807 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: G16H 40/63 for local operation

Abstract

A physiologic data acquisition system includes an analog input, a sigma-delta front end signal conditioning circuit adapted to subtract out DC and low frequency interfering signals from and amplify the analog input before analog to digital conversion. The system can be programmed to acquire a selected physiologic signal, e.g., a physiologic signal characteristic of or originating from a particular biological tissue. The physiologic data acquisition system may include a network interface modulating a plurality of subcarriers with respective portions of an acquired physiologic signal. A receiver coupled to the network interface can receive physiologic data from, and send control signals and provide power to the physiologic data acquisition system over a single pair of wires. The network interface can modulate an RF carrier with the plurality of modulated subcarriers and transmit the resulting signal to the receiver across a wireless network. An integrated circuit may include the physiologic data acquisition system. Also included are methods for acquiring physiologic data comprising the step of selectively controlling an acquisition circuit to acquire the physiologic signal.

Claims

1. A physiologic data acquisition system, comprising:

an analog input;

a sigma-delta front end signal conditioning circuit; and

an output,

the system being programmable to acquire a selected physiologic signal.

2. The system of claim 1, wherein the physiologic signal is an electrophysiologic signal.

3. The system of claim 2, wherein the electrophysiologic signal originates in a tissue selected from heart, brain, skeletal muscle, peripheral nerve, eye, and smooth muscle of the digestive system.

4. The system of claim 1, wherein the physiologic signal relates to blood pressure or blood oxygenation.

5. The system of claim 1, wherein the physiologic signal is light reflected from a physiologic substance.

6. The system of claim 1, wherein the sigma-delta front end signal conditioning circuit comprises a bandpass filter and an amplifier.

7. The system of claim 1, wherein a first acquisition channel in a first integrated acquisition circuit comprises the analog input, the sigma-delta front end signal conditioning circuit, and the output.

8. The system of claim 7, wherein the first integrated acquisition circuit comprises a plurality of acquisition channels, each acquisition channel being programmable to acquire a signal from an independently selected physiological source.

9. The system of claim 8, further comprising a digital multiplexer coupled to each acquisition channel that combines a plurality of digital signals into a serial data stream.

10. The system of claim 9, wherein the first integrated acquisition circuit further comprises the digital multiplexer.

11. The system of claim 9, further comprising a network interface coupled to the digital multiplexer, the network interface modulating a plurality of subcarriers with respective portions of the serial data stream.

12. The system of claim 11, wherein the first integrated acquisition circuit further comprises the network interface.

13. The system of claim 11, further comprising a plurality of integrated acquisition circuits.

14. The system of claim 13, further comprising a receiver networked to the integrated acquisition circuits that receives a plurality of serial data streams from the respective integrated acquisition circuits.

15. The system of claim 14, wherein the receiver sends a plurality of control signals to each respective integrated acquisition circuit and receives the plurality of serial data streams from each respective integrated acquisition circuit over a single pair of wires.

16. The system of claim 15, wherein each integrated acquisition circuit comprises a data output bandpass filter and a control input bandpass filter corresponding respectively to a data input bandpass filter and a control output bandpass filter comprised by the receiver, the receiver receiving the plurality of serial data streams from each respective integrated acquisition circuit at a data frequency corresponding to the data bandpass filters, and the receiver controlling each respective integrated acquisition circuit at a control frequency corresponding to the control bandpass filters.

17. The system of claim 15, wherein the receiver further provides power to each integrated acquisition circuit over the single pair of wires.

18. The system of claim 14, wherein the receiver is networked to the integrated acquisition circuits by a wireless network.

19. The system of claim 18, wherein the network interface modulates an RF carrier with the plurality of modulated subcarriers.

20. The system of claim 1, wherein a first acquisition channel comprises the analog input, the sigma-delta front end signal conditioning circuit, and the output, further comprising a second acquisition channel.

21. The system of claim 20, each acquisition channel being programmable to acquire a signal from an independently selected physiological source.

22. The system of claim 20, further comprising a digital multiplexer coupled to the digital outputs of the acquisition channels that combines a plurality of digital signals into a serial data stream.

23. The system of claim 1, wherein the sigma-delta front end circuit comprises a differential difference amplifier that amplifies the difference between a differential voltage of the analog input and a tracking voltage of a subtraction loop, the subtraction loop coupling the differential difference amplifier output to a subtraction input of the differential difference amplifier.

24. The system of claim 23, wherein the subtraction loop comprises a quantizer.

25. The system of claim 24, wherein the subtraction loop further comprises at least one programmable integrator.

26. The system of claim 25, wherein a first programmable integrator is coupled between the differential difference amplifier output and the quantizer, and a second programmable integrator is coupled between the differential difference amplifier subtraction input and the quantizer.

27. The system of claim 23, further comprising a reconstruction filter coupled to the differential difference amplifier output.

28. The system of claim 8, wherein each sigma-delta front end signal conditioning circuit passband filters each respective analog input signal.

29. The system of claim 8, wherein each sigma-delta front end signal conditioning circuit digitizes each respective analog input signal.

30. A method for acquiring physiologic data, comprising selectively controlling an acquisition circuit to acquire a physiologic signal.

31. The system of claim 30, wherein the physiologic signal is an electrophysiologic signal.

32. The method of claim 31, wherein the electrophysiologic signal originates in a tissue selected from heart, brain, skeletal muscle, peripheral nerve, eye, and smooth muscle of the digestive system.

33. The method of claim 30, further comprising selectively acquiring a plurality of independently selected physiologic signals.

34. The method of claim 30, wherein the acquisition circuit is an integrated acquisition circuit.

35. The method of claim 34, wherein the integrated acquisition circuit comprises a plurality of acquisition channels, further comprising controlling at least two of the acquisition channels to independently acquire their respective physiologic signals.

36. The method of claim 35, further comprising conditioning the physiologic signal in each channel.

37. The method of claim 36, further comprising rejecting a direct current offset of each physiologic signal.

38. The method of claim 36, further comprising rejecting a low frequency component of each physiologic signal.

39. The method of claim 36, further comprising digitizing the physiologic signal in each channel.

40. The method of claim 36, wherein each channel comprises a differential difference amplifier, further comprising employing the differential difference amplifier to amplify the difference between a differential voltage of the respective physiologic signal and a tracking voltage of a subtraction loop, the subtraction loop coupling the differential difference amplifier output to a subtraction input of the differential difference amplifier.

41. The method of claim 40, further comprising quantizing the physiologic signal at the subtraction loop to produce a quantized signal.

42. The method of claim 41, wherein the subtraction loop comprises at least one programmable integrator, further comprising programming a transfer function of the programmable integrator.

43. The method of claim 42, further comprising filtering the quantized signal to reject a high frequency component from the quantized signal to provide a digital output signal.

44. The method of claim 43, further comprising combining the digital output signals from the acquisition channels into a serial data stream.

45. The method of claim 35, further comprising selectively controlling a second integrated acquisition circuit to acquire a physiologic signal.

46. The method of claim 45, further comprising networking the integrated acquisition circuits to a receiver.

47. The method of claim 46, further comprising transmitting the serial data stream from each integrated acquisition circuit to the receiver at a data frequency.

48. The method of claim 47, further comprising transmitting a control signal from the receiver to each integrated acquisition circuit at a control frequency, wherein the control frequency and the data frequency are different.

49. An physiologic data acquisition system, comprising:

means for programming a signal conditioning circuit to condition a signal from a selected physiologic source; and

means for digitizing the conditioned signal.

50. An integrated acquisition circuit, comprising:

a plurality of acquisition channels, each acquisition channel comprising;

an analog input;

a front end signal conditioning circuit, the front end signal conditioning circuit being programmable to acquire a signal from an independently selected source; and

a digital output;

a digital multiplexer coupled to the plurality of acquisition channels that combines a plurality of digital signals into a serial data stream; and

a network interface coupled to the digital multiplexer, the network interface modulating a plurality of subcarriers with respective portions of the serial data stream.

51. The integrated acquisition circuit of claim 50, wherein the front end signal conditioning circuit is a sigma-delta front end signal conditioning circuit.

52. The integrated acquisition circuit of claim 51, further comprising a receiver networked to the integrated acquisition circuit that receives the serial data stream from the integrated acquisition circuit.

53. The integrated acquisition circuit of claim 52, wherein the receiver further sends a control signal to the integrated acquisition circuit and receives the serial data stream from the integrated acquisition circuit over a single pair of wires.

54. The integrated acquisition circuit of claim 53, wherein the receiver further provides power to the integrated acquisition circuit over the single pair of wires.

55. The integrated acquisition circuit of claim 52, wherein the receiver is networked to the integrated acquisition circuits by a wireless network.

56. The integrated acquisition circuit of claim 55, wherein the network interface modulates an RF carrier with the plurality of modulated subcarriers.