ANALOGUE SIGNAL PROCESSORS

• US 20110092834A1
• Filed: 09/14/2010
• Published: 04/21/2011
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: IMEC International, Stichting Imec Nederland
• Original Assignee: IMEC International, Stichting Imec Nederland
• Inventors: KIM, Sunyoung, PENDERS, Julien, YAZICIOGLU, Refet Firat
• Granted Patent: US 8,862,210 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/30 Input circuits therefor
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• 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 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7228 Signal modulation applied to the input signal sent to patient or subject; demodulation to recover the physiological signal modulation H03C
• CPC Class Codes: A61B 5/7232 involving compression of the physiological signal, e.g. to extend the signal recording period
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: G01R 19/2509 Details concerning sampling, digitizing or waveform capturing

Abstract

An analogue signal processor (ASP) application-specific integrated circuit (ASIC) is disclosed. The ACIS can be used for remotely monitoring ECG signals of a subject that has reduced power consumption. In one aspect, the ASIC performs the functions of: ECG signal extraction with high resolution using ECG readout channel, feature extraction using a band-power extraction channel, adaptive sampling the ECG signals using an adaptive sampling analogue-to-digital converter, and impedance monitoring for signal integrity using an impedance monitoring channel. These functions enable the development of wireless ECG monitoring systems that have significantly lower power consumption but are more efficient that predecessor systems. In one embodiment, the ASP ASIC consumes 30 μW from a 2V supply with compression provided by adaptive sampling providing large reductions in power consumption of a wireless ECG monitoring system of which the ASP ASIC forms a part.

Claims

1. An application-specific integrated circuit for cardiac monitoring, the circuit comprising:

an electrocardiogram readout channel having an input and an output, the input being arranged to receive a monitored signal and the output providing a electrocardiogram signal; and

an adaptive sampling unit configured to sample the electrocardiogram signal, the adaptive sampling unit comprising an adaptive threshold generation unit configured to generate a threshold value used to control the adaptive sampling unit.

2. The application-specific integrated circuit according to claim 1, wherein the adaptive sampling unit further comprises an activity detector that includes the adaptive threshold generation unit.

3. The application-specific integrated circuit according to claim 1, further comprising a band-power extraction channel configured to extract power information from the monitored signal.

4. The application-specific integrated circuit according to claim 1;

further comprising an impedance readout channel configured to extract impedance information from the monitored signal.

5. The application-specific integrated circuit according to claim 1, further comprising a stimulation current generator for a device of which the circuit forms a part.

6. The application-specific integrated circuit according to claim 5, wherein the stimulation current generator comprises chopper stabilized AC sources.

7. The application-specific integrated circuit according to claim 1, further comprising an input stage configured to provide the monitored signal to at least the electrocardiogram channel.

8. The application-specific integrated circuit according to claim 7, wherein each input stage comprises an instrumentation amplifier.

9. The application-specific integrated circuit according to claim 1, further comprising at least one output stage.

10. The application-specific integrated circuit according to claim 9, wherein each output stage comprises an instrumentation amplifier.

11. The application-specific integrated circuit according to claim 1, further comprising two low frequency oscillators.

12. The application-specific integrated circuit according to claim 1, further comprising a high frequency oscillator.

13. The application-specific integrated circuit according to claim 1, further comprising a bias circuit generator.

14. The application-specific integrated circuit according to claim 1, further comprising configuration registers.

15. The application-specific integrated circuit according to claim 1, further comprising a digital control circuit.

16. The application-specific integrated circuit according to claim 1, wherein the adaptive sampling unit comprises an analogue-to-digital converter.

17. A medical monitoring device comprising:

the application-specific integrated circuit according to claim 1;

a digital controller configured to process signals output by the application-specific integrated circuit and to provide control signals to the application-specific integrated circuit; and

a wireless module configured to receive data from the digital controller and to transmitting it to a network.

18. A wireless electrocardiogram monitoring system comprising:

a network; and

the medical monitoring device according to claim 17, wherein the wireless module of the medical monitoring device is configured to transmit data to the network.

19. A method of operating a medical monitoring device according to claim 17, the method comprising:

determining a change in an impedance measurement in an electrocardiogram signal with respect to a predetermined threshold value; and

activating processing activities of the device.

20. The method according to claim 19, wherein the processing activities of the device are activated when the impedance measurement falls below the predetermined threshold value.

21. The method according to claim 20, wherein the processing activities of the device are deactivated when the impedance measurement rises above the predetermined threshold value.

22. A method of transferring data from a medical monitoring device according to claim 17, the method comprising:

determining an adaptively sampled ECG signal;

processing the adaptively sampled ECG signal to extract features therefrom; and

transmitting data relating to the extracted features to a host network.

23. The method according to claim 22, wherein data is transferred continuously.

24. The method according to claim 22, wherein data is transferred when a disorder is detected in the extracted features.

25. A method of simultaneously retrieving data from a medical monitoring device according to claim 17, the method comprising:

deriving an electrocardiogram signal; and

deriving at least band-power measurements from the derived electrocardiogram signal.

26. The method according to claim 25, further comprising using the derived band-power measurements for beat detection.

27. The method according to claim 25, further comprising deriving impedance measurements from the derived electrocardiogram signal.

28. The method according to claim 27, further comprising:

removing artifacts from the derived electrocardiogram signal using the derived impedance measurements to provide a compensated electrocardiogram signal; and

using the compensated electrocardiogram signal for beat detection.

29. The method according to claim 27, further comprising:

detecting the presence of artifacts using the derived impedance measurements; and

using the derived band-power measurements for beat detection if no artifacts are detected.

30. The method according to claim 29, further comprising using the derived electrocardiogram signal for beat detection if artifacts are detected.

31. The method according to claim 27, further comprising:

deriving RR intervals from the derived impedance measurements;

determining consistency in derived RR intervals; and

using the derived electrocardiogram signal for beat detection if inconsistency in the RR intervals is determined.