Patent Description:
In many applications, symmetric bidirectional semiconductor devices control the flow of electric current through a circuit.

<CIT> discusses a system and method for ECG electrode and leadwire connection integrity detection. The system includes a plurality of electrodes wherein a uniform spectral energy signal is to be injected into a subset of electrodes of the plurality of electrodes. The system also includes a computing device. The computing device includes a display, and the computing device is communicably coupled to the plurality of electrodes. The computing device is configured to acquire input signals from an electrode and determine a frequency response from the electrode based on the input signal from the electrode. The computing device is also configured to determine impairments in the electrode and leadwire connection using the frequency response.

<CIT> discusses how the output of a random-noise generator is modulated with the aid of two fixed reference frequencies G1, G2 (one of which may be zero) to yield two mutually transposed but correlated noise bands overlapping in a frequency range which substantially coincides with a band of signal frequencies to be transmitted through a test circuit to be examined for second-order and third-order nonlinearities. With the sum or difference of any two correlated signal frequencies Ji', Ji". in the two noise bands equal to a primary beat frequency F1 = G2 ± G1, the amplitude of a signal of this beat frequency in the output of the test circuit receiving the two wholly or partly coincident noise bands is a measure of second-order nonlinearity of that test circuit throughout the signal band. The superposition of a pilot oscillation of frequency G3 (lying within the pass band of the test circuit) upon the primary beat frequency F1 gives rise to a secondary beat frequency F <NUM> = F1 ± G3 whereby the amplitude of another output signal, having this frequency F2, is a measure of third-order nonlinearity of the test circuit.

<CIT> describes an apparatus that includes an electrically-conductive layer, including a first face and a second face that are opposite one another, a first electrically insulative layer that is shaped to define a plurality of apertures and that covers the first face without covering portions of the first face that are aligned with the apertures, and a second electrically-insulative layer that covers the second face.

The present invention is defined by appended claim <NUM>.

There is provided, in accordance with some embodiments of the present invention, a system including a signal generator, configured to pass a generated signal, which has two different generated frequencies, through a circuit including a bidirectional semiconductor device. The system further includes a processor, configured to identify, while the generated signal is passed through the circuit, a derived frequency, which derives from the generated frequencies, on the circuit. The processor is further configured to generate, in response to identifying the derived frequency, an output indicating that a property of the bidirectional semiconductor device is asymmetric.

In some embodiments, the processor is configured to identify the derived frequency over an electrophysiological channel belonging to the circuit.

In some embodiments, the derived frequency is within a bandwidth of an electrophysiological signal carried over the.

In some embodiments, each of the generated frequencies is outside the bandwidth.

In some embodiments, the property includes an impedance.

In some embodiments, the derived frequency is a difference between the generated frequencies.

In some embodiments, the processor is further configured to disable a power source connected to the circuit in response to detecting the derived frequency.

In some embodiments, the power source is selected from the group of power sources consisting of: a cardiac defibrillator, a cardiac pacer, and an ablation generator.

In some embodiments, the bidirectional semiconductor device belongs to a voltage suppressor.

In some embodiments, the bidirectional semiconductor device belongs to a semiconductor switch.

There is further provided, in accordance with some embodiments presently not claimed, a method including passing a generated signal, which has two different generated frequencies, through a circuit including a bidirectional semiconductor device. The method further includes, while passing the two generated signals through the circuit, identifying a derived frequency, which is derived from the generated frequencies, on the circuit. The method further includes, in response to identifying the derived frequency, generating an output indicating that a property of the bidirectional semiconductor device is asymmetric.

There is further provided, in accordance with some embodiments of the present disclosure, a system including a signal generator, configured to pass a generated signal, which has two different generated frequencies, through a circuit including an intrabody electrode. The system further includes a processor, configured to identify, while the generated signal is passed through the circuit, a derived frequency, which is derived from the generated frequencies, on the circuit. The processor is further configured to generate, in response to identifying the derived frequency, an output indicating a flaw in the electrode.

In some embodiments, each of the generated frequencies is less than <NUM>.

In some embodiments, an amplitude of the generated signal is less than <NUM>µA.

In some embodiments, the signal generator is configured to pass the generated signal through the circuit while the electrode is submerged in an electrolytic solution.

In some embodiments, the electrolytic solution includes saline.

In some embodiments, the electrode belongs to an intrabody probe.

In some embodiments, the system further includes a kit including:.

In some embodiments, the kit further includes a communication interface, and the processor is configured to identify the derived frequency by processing an output signal received from the kit via the communication interface.

In some embodiments, the electrode is one of a plurality of electrodes belonging to the probe, and the kit further includes a multiplexer configured to selectively connect the electrodes to the signal generator.

There is further provided, in accordance with some embodiments presently not claimed, a method including passing a generated signal, which has two different generated frequencies, through a circuit including an intrabody electrode. The method further includes, while passing the generated signal through the circuit, identifying a derived frequency, which is derived from the generated frequencies, on the circuit. The method further includes, in response to detecting the derived frequency, generating an output indicating a flaw in the electrode.

In the context of the present application, including the claims, the term "bidirectional semiconductor device" may refer to any semiconductor device configured to conduct both the positive and negative portions of an alternating current (AC) signal. If a property (e.g., the impedance) of the bidirectional semiconductor device is the same for both portions of the signal, the property (or the device itself) is said to be "symmetric;" otherwise, the property (or the device itself) is said to be "asymmetric.

In many cases, it is desired that a bidirectional semiconductor device in a circuit have symmetric properties, such that an alternating current (AC) passing through the device does not generate any direct current (DC) voltage. For a circuit connected to an intrabody probe, such as an electrophysiological probe, disposed within the body of a subject, this symmetry is particularly important, as any DC voltages generated, for example, from the flow of ablative radiofrequency (RF) currents through the bidirectional semiconductor device, are likely to be dangerous to the subject. Hence, there is a need for fast and effective detection of any asymmetry in a bidirectional semiconductor device.

To address this need, exemplary embodiments of the present invention provide a system for testing the symmetry of a bidirectional semiconductor device in a circuit. The system comprises a signal generator connected to the circuit and configured to generate a signal having two different frequencies. Provided that the bidirectional semiconductor device is symmetric, the bidirectional semiconductor device behaves as a linear device, and hence does not generate any additional frequencies. However, in the event that the bidirectional semiconductor device is asymmetric (e.g., by virtue of having an asymmetric impedance), the device behaves non-linearly, thus causing other "derived" frequencies, which derive from the frequencies of the generated signal, to be carried on the circuit. Hence, by identifying one of these derived frequencies, such as the difference between the frequencies of the generated signal, the asymmetry may be detected.

Advantageously, for electrophysiological applications, the derived frequencies may be detected over a preexisting electrophysiological channel, such that the symmetry testing described herein may not require additional hardware. To BIO6343USNP1 facilitate this, the frequencies of the generated signal may be chosen such that the difference between the frequencies falls within the bandwidth of the electrophysiological signal carried over the channel. Nonetheless, the frequencies themselves may be chosen to fall outside this bandwidth, such that the generated signal does not interfere with the detection of the electrophysiological signal.

Exemplary embodiments of the present disclosure further provide a testing kit for testing the quality of an electrode while the electrode is submerged in an electrolytic solution. The kit, which comprises the aforementioned signal generator, is connected to the electrode, such that the generated signal flows through the electrode. In the event of a flaw in the surface of the electrode (e.g., in the event that the surface is rough or dirty), the non-linearity of the interface between the electrode and the electrolytic solution is increased, such that the amplitude with which derived frequencies are generated is also increased. Hence, by identifying one of the derived frequencies, the flaw may be detected.

Reference is initially made to <FIG>, which is a schematic illustration of an electrophysiological system <NUM>, in accordance with some exemplary embodiments of the present invention.

System <NUM> comprises an intrabody probe <NUM>, comprising one or more intrabody electrodes <NUM> disposed at the distal end thereof. Using probe <NUM> and electrodes <NUM>, a physician <NUM> may acquire electrophysiological signals from a subject <NUM>, such as electrogram signals from the heart <NUM> of subject <NUM>. Alternatively or additionally, the physician <NUM> may use the probe <NUM> and electrodes <NUM> to pace or to defibrillate heart <NUM>, or to ablate tissue of the heart <NUM>.

Probe <NUM> is proximally connected to circuitry <NUM>, which is typically contained in a console <NUM>. Typically, system <NUM> further comprises a processor <NUM> and a monitor <NUM>. In response to output from circuitry <NUM>, processor <NUM> may display relevant output on monitor <NUM>, as further described below with reference to <FIG>.

In general, processor <NUM> may be embodied as a single processor, or as a cooperatively networked or clustered set of processors. In some exemplary embodiments, the functionality of processor <NUM>, as described herein, is implemented solely in hardware, e.g., using one or more Application-Specific Integrated Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs). In other exemplary embodiments, the functionality of processor <NUM> is implemented at least partly in software. For example, in some exemplary embodiments, processor <NUM> is embodied as a programmed digital computing device comprising at least a central processing unit (CPU) and random-access memory (RAM). Program code, including software programs, and/or data are loaded into the RAM for execution and processing by the CPU. The program code and/or data may be downloaded to the processor in electronic form, over a network, for example. Alternatively or additionally, the program code and/or data may be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory. Such program code and/or data, when provided to the processor, produce a machine or special-purpose computer, configured to perform the tasks described herein.

Reference is now made to <FIG>, which is a schematic illustration of circuitry <NUM>, illustrated in <FIG>, in accordance with some exemplary embodiments of the present invention.

Circuitry <NUM> comprises at least one digitizer <NUM>, configured to digitize electrophysiological signals from the electrodes <NUM> and to output the digitized signals <NUM> to processor <NUM> (<FIG>) over a wired or wireless connection. Digitizer <NUM> may comprise any suitable filters for filtering the signals prior to digitization.

Typically, circuitry <NUM> further comprises at least one power source configured to deliver power to the electrodes. For example, circuitry <NUM> may comprise a cardiac pacer <NUM>, a cardiac defibrillator, and/or an ablation generator. Typically, the circuitry further comprises at least one voltage suppressor <NUM>, which suppresses voltages delivered by the power source.

For exemplary embodiments in which the probe comprises multiple electrodes, the circuitry typically comprises different respective electrophysiological channels for the electrodes. Each channel comprises a separate digitizer <NUM> and voltage suppressor <NUM>, which are typically connected to the electrode, in parallel to one another, via a resistor <NUM>. Circuitry <NUM> may further comprise a multiplexer <NUM>, which comprises multiple semiconductor switches <NUM>, and a multiplexer controller <NUM>. Multiplexer controller <NUM> is configured to control switches <NUM> so as to selectively connect the channels to the power source.

In general, the circuitry may comprise any number of electrodes, and hence, any number of channels. By way of example, <FIG> shows an embodiment in which the probe comprises two electrodes, referred to in the figure as "electrode <NUM>" and "electrode <NUM>," and circuitry <NUM> correspondingly comprises two channels, referred to in the figure as "channel <NUM>" and "channel <NUM>.

Circuitry <NUM> comprises at least one bidirectional semiconductor device.

For example, each switch <NUM> may comprise a bidirectional semiconductor device. As a specific example, each switch <NUM> may comprise a light-emitting diode (LED) <NUM> along with a pair of phototransistors <NUM> connected to one another and to a pair of parasitic diodes <NUM>. In response to a control signal from BIO6343USNP1 multiplexer controller <NUM>, LED <NUM> may emit light toward phototransistors <NUM>, thus causing the phototransistors to become conductive. Current (e.g., from pacer <NUM>) may then flow through the switch.

Alternatively or additionally, each voltage suppressor <NUM> may comprise a bidirectional semiconductor device. For example, each voltage suppressor <NUM> may comprise a pair of diodes <NUM> or thyristors connected to one another, in series or in parallel, in opposing orientations. Diodes <NUM> may comprise avalanche or Zener diodes, for example.

Advantageously, circuitry <NUM> is configured to test the symmetry of any of the bidirectional semiconductor devices belonging to the circuitry. To facilitate this testing, the circuitry comprises at least one signal generator <NUM> configured to generate a signal having a first frequency f1 and a second frequency f2. Typically, the amplitude of the generated signal is relatively low, such as less than <NUM>µA, so as not to pose a risk to the subject. In the event that the impedance or another property (e.g., the cutoff voltage) of one of the bidirectional semiconductor devices is asymmetric, the device behaves non-linearly, thus generating other frequencies derived from f1 and f2, such as frequencies that are linear combinations of f1 and f2. By identifying linear combinations of f1 and f2, such as the beat frequency |f1-f2|, f1+f2, 2f1+f2, or |2f1-f2|, in digitized signal <NUM>, the processor may detect the asymmetry.

In some exemplary embodiments, signal generator <NUM> comprises a voltage source. In such exemplary embodiments, as shown in <FIG>, the signal generator may be modeled as a first voltage source 50a, configured to generate a first signal having first frequency f1, and a second voltage source 50b, configured to generate a second signal having second frequency f2, each of the voltage sources being connected in series with a respective resistor <NUM>. In other exemplary embodiments, signal generator <NUM> comprises a current source.

In some exemplary embodiments, circuitry <NUM> comprises a different respective signal generator for each channel. In other exemplary embodiments, a single signal generator is connected, via a multiplexer, to all of the channels.

Typically, f1 and f2 lie outside the bandwidth of (i.e., outside the range of frequencies exhibited by) the electrophysiological signal carried over the channel, such that the generated signal does not interfere with the processing of the electrophysiological signal. For example, for applications in which electrogram signals are carried over the channels, each of the generated frequencies may be greater than <NUM>, such as greater than <NUM>. Nevertheless, at least one derived frequency, such the difference between f1 and f2, is typically within the aforementioned bandwidth, such that the sampling rate of the digitizer, which generally corresponds to the highest frequency in the bandwidth, is sufficient for capturing the derived frequency. For example, for electrogram applications, the derived frequency may be less than <NUM>, such as between <NUM> and <NUM>. Thus, advantageously, the derived frequency may be identified in signal <NUM>, i.e., the regular digitized electrophysiological signal received from digitizer <NUM>.

In response to identifying the derived frequency (e.g., in response to identifying a component of signal <NUM> having the derived frequency and an amplitude greater than a predefined threshold), the processor may generate an output indicating that the impedance of the bidirectional semiconductor device is asymmetric, e.g., by displaying a suitable warning on monitor <NUM> (<FIG>). Alternatively or additionally, in response to identifying the derived frequency, the processor may disable the power source.

Reference is now made to <FIG>, which is a schematic illustration of a system <NUM> for testing the quality of electrodes <NUM> prior to the use of probe <NUM>, in accordance with some exemplary embodiments of the present disclosure.

System <NUM> comprises signal generator <NUM>, which as set forth above with respect to <FIG>, may be modeled as a first voltage source 50a, configured to generate a first signal having first frequency f1, and a second voltage source 50b, configured to generate a second signal having second frequency f2, each of the voltage sources being connected in series with a respective resistor <NUM>, and digitizer <NUM>, which is configured to communicate with a processor <NUM> over a wired or wireless connection. To test each electrode, the generated signal from the signal generator is passed through a circuit including the electrode. While the generated signal is passed through the circuit, processor <NUM> monitors the circuit for a derived frequency, such as |f1 - f2|, by processing digitized signal <NUM>, as described above with reference to <FIG>. In response to identifying the derived frequency (e.g., in response to identifying a component of signal <NUM> having the derived frequency and an amplitude greater than a predefined threshold), the processor <NUM> generates an output indicating a flaw in the electrode.

Typically, the signal generator and digitizer belong to a testing kit <NUM> configured to connect to the probe <NUM>, e.g., to the proximal end thereof. Typically, testing kit <NUM> further comprises multiplexer <NUM> (which may comprise switches of any type) and multiplexer controller <NUM>. Each switch in multiplexer <NUM> is configured to connect, via a different respective wire, to a different respective electrode at the distal end of the probe <NUM>. The wires may be contained in a cable <NUM>, which may be connected to the probe <NUM> via a suitable interface in a handle <NUM> of the probe <NUM>. In response to a control signal <NUM> from processor <NUM>, multiplexer controller <NUM> controls multiplexer <NUM> such that the multiplexer selectively connects the electrodes to the signal generator for testing.

In general, processor <NUM> may be embodied as a single processor, or as a cooperatively networked or clustered set of processors. In some exemplary embodiments, the functionality of processor <NUM>, as described herein, is implemented solely in hardware, e.g., using one or more Application-Specific Integrated Circuits (ASICs) or Field-Programmable Gate Arrays (FPGAs). In other exemplary embodiments, the functionality of processor <NUM> is implemented at least partly in software, as described above for processor <NUM> (<FIG>). Processor <NUM> may belong to testing kit <NUM> or, as implied by <FIG>, to an external computer. In response to identifying the derived frequency, the processor <NUM> may display a suitable warning on a computer monitor, output an audio alert, and/or generate another output, such as by activating a warning light belonging to the testing kit.

Typically, electrodes <NUM> are tested while submerged in an electrolytic solution <NUM>, such as saline, which simulates an intrabody environment. The non-linearity of the impedance at the interface between each electrode and solution <NUM>, and hence, the amplitude of any derived-frequency components of signal <NUM>, increases with the degree to which the surface of the electrode is flawed, e.g., rough or dirty. Hence, as described above, flaws may be detected in response to identifying the derived frequencies in signal <NUM>.

Typically, a return electrode <NUM>, which is typically disposed at the bottom of the container <NUM> containing solution <NUM>, is connected, via a wire <NUM>, to the testing kit. Wire <NUM> may be contained in a cable. Thus, the testing circuit through which the generated signal is passed includes solution <NUM>, return electrode <NUM>, and wire <NUM>.

In general, the testing kit may comprise a case made of any suitable material, such as a plastic, configured to hold the various components of the kit described herein. The testing kit may comprise any suitable electrical interface, such as a port or socket, for connecting the kit to the probe such that electrodes <NUM> are connected to the signal generator. Similarly, the testing kit may comprise any suitable electrical interface for connecting the kit to return electrode <NUM>. Alternatively or additionally, the testing kit may comprise any suitable wired or wireless communication interface (e.g., a Universal Serial Bus (USB) port) for communicating with processor <NUM>, such that the processor may receive signal <NUM> from the kit, and/or the kit may receive control signal <NUM> from the processor, via the communication interface.

Claim 1:
A system (<NUM>) for testing the symmetry of a bidirectional semiconductor device (<NUM>) in a circuit (<NUM>) connected to an intrabody probe, the system comprising:
a signal generator, configured to pass a generated signal, which has two different generated frequencies, through the circuit including a bidirectional semiconductor device; and
a processor (<NUM>), configured to:
while the generated signal is passed through the circuit (<NUM>), identify a derived frequency, which derives from the generated frequencies, on the circuit (<NUM>), and
in response to identifying the derived frequency, generate an output indicating that a property of the bidirectional semiconductor device (<NUM>) is asymmetric;
wherein the derived frequency is a linear combination of the generated frequencies;