Patent Description:
Each transducer array used for the delivery of TTFields in the OPTUNE® device comprises a set of non-conductive ceramic disk electrodes, which are coupled to the patient's skin (such as, but not limited to, the patient's shaved head for treatment of GBM) through a layer of conductive medical gel. To form the ceramic disk electrodes, a conductive layer is formed on a top surface of nonconductive ceramic material. A bottom surface of the nonconductive ceramic material is coupled to the conductive medical gel. The nonconductive ceramic material is a safety feature to ensure that direct-current signals are blocked from unintentionally being transmitted to the patient by mistake. By interposing a nonconductive ceramic material between the conductive layer and the conductive medical gel, the prior art system was thought to ensure the patient remains protected. The purpose of the medical gel is to deform to match the body's contours and to provide good electrical contact between the arrays and the skin; as such, the gel interface bridges the skin and reduces interference. The device is intended to be continuously worn by the patient for <NUM>-<NUM> days before removal for hygienic care and re-shaving (if necessary), followed by reapplication with a new set of arrays. As such, the medical gel remains in substantially continuous contact with an area of the patient's skin for a period of <NUM>-<NUM> days at a time, and there is only a brief period of time in which the area of skin is uncovered and exposed to the environment before more medical gel is applied thereto.

One approach to applying the TTField in different directions is to apply the field between a first set of electrodes for a period of time, then applying a field between a second set of electrodes for a period of time, then repeating that cycle for an extended duration (e.g., over a period of days or weeks).

In order to generate the TTFields, current is applied to each electrode of the transducer array. The application of current over a period of time causes each electrode to warm and eventually become hot, and thus may become uncomfortable or painful to the patient. As such, the amplitude of the alternating current that is delivered via the transducer arrays may be controlled so that skin temperature (as measured on the skin below the transducer arrays) does not exceed a safety threshold (e.g., <NUM> degrees Celsius, for example). The temperature measurements on the patient's skin are obtained using temperature sensors (e.g., thermistors) placed beneath some of the disks of the transducer arrays. For example, each array may include eight thermistors, with one thermistor positioned beneath a respective disk in the array.

The thermistors in each array are connected via long wires to an electronic device called the "cable box" where the temperature from all thermistors (e.g., four arrays × eight thermistors per array) is measured and analog-to-digital converted into digital values for each thermistor. These measurements are then transmitted from the cable box to the electric field generator via additional wire(s) that facilitate two-way digital serial communications between the cable box and the field generator. The controller in the field generator uses the temperature measurements to control the current to be delivered via each pair of arrays in order to maintain temperatures below, for example, <NUM> degrees Celsius on the patient's skin. The current itself is delivered to each array via an additional wire (i.e., one wire for each array) that runs from the field generator through the cable box to the array. However, attaching temperature sensors and transducer arrays to a patient is cumbersome with the amount of wires.

<CIT> discloses delivering tumor treating fields (TTFields) to a subject's body at higher field strengths by switching off one or more electrode elements that are overheating without switching off other electrode elements that are not overheating; being accomplished using a plurality of temperature sensors, with each of the temperature sensors positioned to sense the temperature at a respective electrode element, and a plurality of electrically-controlled switches, each of which is wired to switch the current to an individual electrode element on or off.

<CIT> discloses delivering tumor treating fields (TTFields) by implanting a plurality of sets of implantable electrode elements within a person's body, with temperature sensors positioned to measure the temperature at the electrode elements also being implanted, along with a circuit that collects temperature measurements from the temperature sensors.

<CIT> discloses systems and methods for measuring the temperature at the electrode elements of transducer arrays that are used to apply tumor treating fields (TTFields) to a subject, with a distal circuit being positioned adjacent to each transducer array, and the distal circuit interfacing with temperature sensors in the transducer array to obtain temperature readings.

<CIT> discloses inhibiting the spreading of cancer cells in a target region by imposing a first AC electric field in the target region for a first interval of time, with a frequency and amplitude selected to disrupt mitosis of the cancer cells, and a second AC electric field in the target region for a second interval of time, with a frequency and the amplitude selected to reduce motility of the cancer cells.

One aspect of the invention is directed to an apparatus for imposing electric fields through a target region in a body of a patient according to claim <NUM>.

Before explaining at least one embodiment of the inventive concept(s) in detail by way of exemplary language and results, it is to be understood that the inventive concept(s) is not limited in its application to the details of construction and the arrangement of the components set forth in the following description. The language used herein is intended to be given the broadest possible scope and meaning; and the embodiments are meant to be exemplary - not exhaustive.

Unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

As utilized in accordance with the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings:
The use of the term "a" or "an" when used in conjunction with the term "comprising" in the claims and/or the specification may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one. " As such, the terms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to "a compound" may refer to one or more compounds. The term "plurality" refers to "two or more.

The use of the term "at least one" will be understood to include one as well as any quantity more than one. In addition, the use of the term "at least one of X, Y, and Z" will be understood to include X alone, Y alone, and Z alone, as well as any combination of X, Y, and Z. The use of ordinal number terminology (i.e., "first," "second," "third," "fourth," etc.) is solely for the purpose of differentiating between two or more items and is not meant to imply any sequence or order or importance to one item over another or any order of addition, for example.

The use of the term "or" in the claims is used to mean an inclusive "and/or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive. For example, a condition "A or B" is satisfied by any of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

As used herein, any reference to "one embodiment," "an embodiment," "some embodiments," "one example," "for example," or "an example" means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment.

Throughout this application, the term "about" is used to indicate that a value includes the inherent variation of error for an apparatus/device, the method being employed to determine the value, or the variation that exists among the study subjects.

As used in this specification and claim(s), the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include"), or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

As used herein, the term "substantially" means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance occurs to a great extent or degree. For example, when associated with a particular event or circumstance, the term "substantially" means that the subsequently described event or circumstance occurs at least <NUM>% of the time, or at least <NUM>% of the time, or at least <NUM>% of the time, or at least <NUM>% of the time. For example, the term "substantially adjacent" may mean that two items are <NUM>% adjacent to one another, or that the two items are within close proximity to one another but not <NUM>% adjacent to one another, or that a portion of one of the two items is not <NUM>% adjacent to the other item but is within close proximity to the other item.

The term "patient" as used herein includes human and veterinary subjects. "Mammal" for purposes of treatment refers to any animal classified as a mammal, including (but not limited to) humans, domestic and farm animals, nonhuman primates, and any other animal that has mammary tissue.

Circuitry, as used herein, may be analog and/or digital components, or one or more suitably programmed processors (e.g., microprocessors) and associated hardware and software, or hardwired logic. Also, "components" may perform one or more functions. The term "component," may include hardware, such as a processor (e.g., microprocessor), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a combination of hardware and software, and/or the like. The term "processor" as used herein means a single processor or multiple processors working independently or together to collectively perform a task.

As discussed above, attaching temperature sensors and transducer arrays to a patient is cumbersome with the amount of wires. As such, the inventor has recognized a need for new and improved array assemblies that reduce the number of wires, which may increase patient comfort and reduce cost. It is to such assemblies and methods of producing and using the same, that the present disclosure is directed.

Turning now to the inventive concept(s), certain non-limiting embodiments thereof include an apparatus for imposing electric fields through a target region in a body of a patient is described. The apparatus may comprise at least one transducer array, a sensor array, a circuit and a controller. The at least one transducer array has a plurality of electrode elements configured for placement on the body of the patient, the electrode elements configured to provide TTFields via an alternating current waveform. The sensor array has a plurality of temperature sensors positioned within proximity to the plurality of electrode elements, a plurality of first temperature sensors of the sensor array connected to a first conductor, and a plurality of second temperature sensors connected to a second conductor. The circuit is configured to provide a known amount of electricity via the first conductor and the second conductor to a third temperature sensor, the third temperature sensor within the first plurality of first temperature sensors, and within the second plurality of second temperature sensors, and obtain a first electrical reading corresponding to a first temperature reading of the third temperature sensor. The controller adjusts the alternating current waveform based on the first temperature reading.

Referring now to the drawings, and in particular <FIG> and <FIG>, shown therein are block diagrams of an exemplary embodiment of a system <NUM> having one or more circuit <NUM>. The circuit <NUM> is described herein by way of example as one or more distal circuits <NUM> positioned in close proximity to one or more transducer arrays <NUM> to obtain one or more temperature readings from one or more temperature sensors <NUM>. Each of the transducer arrays <NUM> includes one or more electrode elements <NUM>. Alternative constructions for the transducer arrays <NUM> may also be used, including, for example, transducer arrays using ceramic elements that are not disc-shaped, and/or transducer arrays that use non-ceramic dielectric materials positioned over a plurality of flat conductors. Examples of the latter include polymer films disposed over pads on a printed circuit board or over flat pieces of metal. Transducer arrays that use electrode elements that are not capacitively coupled may also be used. In this situation, each element of the transducer array may be implemented using a region of a conductive material that is configured for placement against a person's body, with no insulating dielectric layer disposed between the conductive elements and the body. Examples of the conductive material include, but are not limited to, a conductive film, a conductive fabric, and/or a conductive foam. Other alternative constructions for implementing the transducer arrays may also be used, as long as they are (a) capable of delivering TTFields to the person's body and (b) utilize the improved connector designs described herein positioned in the locations specified herein. Optionally, a layer of hydrogel may be disposed between the transducer arrays and a body of a person in any of the embodiments described herein.

The one or more temperature sensors <NUM> are positioned to detect the temperature at the electrode elements <NUM>. In some embodiments, the temperature sensors <NUM> may be thermistors, thermocouples, resistance temperature detectors (RTDs), integrated circuit temperature sensors such as the Analog Devices AD590 and the Texas Instruments LM135, and/or combinations thereof.

Each distal circuit <NUM> interfaces with the one or more temperature sensors <NUM> that are incorporated into the respective transducer array <NUM> to obtain temperature readings from each of the one or more temperature sensor <NUM>. The distal circuit <NUM> then may convert (e.g., analog to digital) the temperature readings, forward the temperature reading and/or send the temperature readings to a hub <NUM>. The hub <NUM> may then forward the temperature reading and/or send the temperature readings to a field generator <NUM> (e.g., via a serial communication link). In some embodiments, the field generator <NUM> may determine, based on the temperature readings, adjustment of the current to the transducer arrays <NUM>.

In some embodiments, conductors <NUM> may extend distally beyond the distal circuit <NUM> into the transducer array <NUM>. Each temperature sensor <NUM> may be connected to at least two conductors <NUM> such that selective activation of the at least two conductors <NUM> may activate the temperature sensor <NUM> to obtain one or more temperature readings (e.g., selective activation on a time basis).

Additionally, wiring extending from the distal circuit <NUM> may include but is not limited to, one or more conductors for the one or more temperature sensors' common ground, and one or more conductors for the TTFields signal (i.e., the AC current for the electrode elements), and the like. In some embodiments, the distal circuit <NUM> may be implemented using a single-chip microcontroller or Programmable System on Chip (PSoC) with a built in analog front end and multiplexer. Suitable part numbers for this purpose include the CY8C4124LQI-<NUM>, manufactured by Cypress Semiconductor Corp. , having a principle place of business in San Jose, California.

As one skilled in the art will appreciate, some embodiments may include one or more microcontrollers having built-in and/or discrete analog front ends and/or multiplexers. For example, the analog front end and multiplexer may obtain temperature readings from the one or more temperature sensors <NUM>. Those temperature readings may then be digitized and/or transmitted to the hub <NUM>, (e.g., via serial data link). In some embodiments, each distal circuit <NUM> may also include one or more pass-through conductors <NUM> (see <FIG>). The one or more pass-through conductors <NUM> may be configured to route one or more TTFields signal that originated in the field generator <NUM> to the transducer array <NUM>.

In some embodiments, each distal circuit <NUM> may be connected to the hub <NUM> via one or more cable <NUM>. Conductors <NUM> in each cable <NUM> may run between the distal circuit <NUM> and the hub <NUM>. For example, in <FIG>, four conductors <NUM> run between each distal circuit <NUM> and the hub <NUM>, including, one conductor <NUM> for power (Vcc), one conductor <NUM> for grounding (GND), one conductor for serial data communication (DATA), and one for the TTF signal.

Generally, the hub <NUM> may receive one or more temperature readings from each of the distal circuits <NUM> and may send the one or more temperature readings to the field generator <NUM>. Any of a wide variety of architectures may be used to receive and send the one or more temperature readings. For example, <FIG> illustrates a controller <NUM> configured to send a signal to a digital multiplexer (Digital MUX) <NUM> that commands the digital multiplexer <NUM> to select one of the distal circuits <NUM> such that the hub <NUM> may receive digital data from the distal circuit <NUM> (e.g., the first distal circuit <NUM>).

The controller <NUM> receives the one or more temperature readings from the selected input of the distal circuit <NUM> and transmits the one or more temperature readings to the field generator <NUM> via the transceiver <NUM>. The controller <NUM> may then update the control signal to the digital multiplexer <NUM> such that the digital multiplexer <NUM> selects another distal circuit <NUM> (e.g., the second distal circuit <NUM>). The controller <NUM> then receives one or more temperature readings from the input of the second distal circuit <NUM> and transmits one or more temperature readings to the field generator <NUM>. Corresponding sequences may be then performed to obtain suitable temperature readings (e.g., nine temperature readings) from each of the distal circuits <NUM>. In some embodiments, the entire sequence of obtaining each of the one or more temperature readings from each of the distal circuits <NUM> or a portion of the sequence may be repeated periodically (e.g., every <NUM>/<NUM> second, <NUM> second, <NUM> seconds, or <NUM> seconds, etc.) to update the one or more temperature readings that are provided to the field generator <NUM>.

In some embodiments, the controller <NUM>, the digital multiplexer <NUM>, and/or the transceiver <NUM> may be integrated together into a single chip. In some embodiments, the controller <NUM> and the digital multiplexer <NUM> may be integrated together into circuitry including a single chip, and a separate transceiver <NUM> is used. For example, the controller <NUM> and the digital multiplexer <NUM> may be implemented using a Cypress CY8C4244LQI-<NUM>, manufactured by Cypress Semiconductor Corp. , having a principle place of business in San Jose, California, and the transceiver <NUM> may be implemented using a Linear Technology LTC2856CMS8-<NUM>#PBF, manufactured by Linear Technology Corp. , having a principle place of business in Milpitas, California. The controller <NUM> and/or the digital multiplexer <NUM> may be implemented as a processor executing software to perform the functions described herein.

The hub <NUM> may communicate with the field generator <NUM> using any conventional communication technique (e.g., RS485). In some embodiments, the hub <NUM> may include one or more pass-through conductors configured to pass one or more TTField signals directly from the field generator <NUM> to each of the transducer arrays <NUM>. In some embodiments, the hub <NUM> may communicate with the field generator <NUM> via an <NUM>-conductor spiral cable <NUM>, optionally connecting via a connector <NUM> (<FIG>). For example, the hub <NUM> may communicate with the field generator <NUM> via an <NUM>-conductor spiral cable <NUM> wherein four wires (e.g. P1, P2, N1, N2) may provide for TTFields signals from each transducer array <NUM>, one wire may provide for ground (GND), one wire may provide for voltage (Vcc) to the distal circuits <NUM>, and two wires may provide for communication (RS485A and RS485B). It should be noted that use of <NUM>-conductor spiral cable <NUM> is configured to be backwards compatible with prior versions of TTField delivery systems within the art as one skilled in the art will appreciate.

Communication wires may be configured to implement data communications between the distal circuit <NUM>, the hub <NUM> and the field generator <NUM> (i.e., for the temperature data). In some embodiments, one wire may be configured to implement communication in each direction. In some embodiments, wire count between the hub <NUM> and the field generator <NUM> can be reduced by replacing multiple data communication wires with a single data wire that implements two-way communication (using a conventional single wire communication protocol).

<FIG> is a schematic diagram of an exemplary distal circuit <NUM> for interfacing the hub <NUM> with the one or more transducer array <NUM>. Each transducer array <NUM> may include one or more electrode elements <NUM> and one or more temperature sensors <NUM> (e.g. 16a-i in <FIG>) positioned to sense temperatures of the one or more electrode elements <NUM>. The one or more temperature sensors <NUM> may include, but are not limited to, thermistors, thermocouples, RTDs, integrated circuit temperature sensors such as the Analog Devices AD590 and the Texas Instruments LM135, and/or combinations thereof. It is contemplated that any temperature sensor <NUM> known within the art may be used if configured to provide an accurate and/or precise temperature reading in accordance with the present disclosure. In some embodiments, one or more temperature sensors <NUM> may be thermistors.

The distal circuit <NUM> may include a first multiplexer (MUX <NUM>) 60a and a second multiplexer (MUX <NUM>) 60b. Generally, the first multiplexer 60a drives a known amount of electricity (e.g., current) to the one or more temperature sensor <NUM> and the second multiplexer 60b electrically connects one or more temperature sensor <NUM> to a reference point (e.g., GND).

The first multiplexer 60a includes an output 62a and one or more selectable inputs 64a. Each of the one or more selectable inputs 64a may be connected to two or more temperature sensors <NUM>. Similarly, the second multiplexer 60b includes an output 62b and one or more selectable inputs 64b. Each of the one or more selectable inputs 64b may be connected to two or more temperature sensors <NUM>. To that end, each temperature sensor <NUM> may be connected to at least two conductors <NUM>. At least one terminal 64c may be a common ground. In some embodiments, the output 62a of the first multiplexer 60a may be provided to an input <NUM> of an amplifier <NUM>, (e.g., amplifier having a high input impedance such as an op amp configured as a voltage follower). Output <NUM> of the amplifier <NUM> may be provided to an input <NUM> of an analog to digital converter (ADC) <NUM>. Output <NUM> of the analog to digital converter is provided to input <NUM> of a controller <NUM>. The controller <NUM> may include circuitry including but not limited to a processor executing computer executable instructions, e.g., software, to perform the functions described herein.

In some embodiments, the controller <NUM> may be configured to orchestrate operation of one or more of the components within the dashed line <NUM>. The controller <NUM> may be configured to send one or more commands to the first multiplexer 60a and second multiplexer 60b to select two or more conductors <NUM> in communication with one of the temperature sensors <NUM>, in order to obtain a temperature reading from that temperature sensor <NUM>. In some embodiments, the first multiplexer 60a and 60b are configured to provide an open circuit with respect to the unselected conductors <NUM> so that only a particular one of the temperature sensors <NUM> is read at any particular instant of time.

In some embodiments, temperature readings may be obtained by routing a known amount of electricity, e.g., current, through the at least two conductors <NUM> to the temperature sensor <NUM> (e.g., thermistor) and measuring an electrical reading, e.g., voltage, that appears across the temperature sensor <NUM>. For example, a programmable current source <NUM> may be configured to generate a known current (e.g., 150µA) through the at least two conductors <NUM>. The first multiplexer 60a may be bidirectional such that the known current may be routed to the temperature sensor <NUM> via the selected conductors <NUM> by the first multiplexer 60a.

Referring to <FIG> and <FIG>, temperature readings obtained from temperature sensors <NUM> within a sensor array 90a may be obtained using selective activation of at least two conductors <NUM>. A plurality of first temperature sensors 16a, 16d, and <NUM>, for example, of the sensor array 90a are connected to a first conductor 30a. A plurality of second temperature sensors 16a, 16b and 16c, for example, of the sensor array 90a are connected to a second conductor 30d. The controller <NUM> sends one or more commands to the first multiplexer 60a and the second multiplexer 60b to select at least two conductors 30a and 30d in communication with a third temperature sensor 16a within the sensor array 90a, and configures the current source <NUM> to generate a known current via the two conductors 30a and 30d. In this example, the third temperature sensor 16a is within the plurality of first temperature sensors (16a, 16d and <NUM>) and also within the plurality of second temperature sensors (16a, 16b, and 16c).

The known current from the current source <NUM> is configured to flow through the first multiplexer 60a to the third temperature sensor 16a via the two conductors 30a and 30d connected to the third temperature sensor 16a resulting in a voltage appearing across the third temperature sensor 16a and at the output 62a of the first multiplexer 60a. In some embodiments, the known current from the current source <NUM> is configured to flow through the first multiplexer 60a to the third temperature sensor 16a via the two conductors 30a and 30d connected to the third temperature sensor 16a resulting in a voltage appearing across the third temperature sensor 16a and the output 62a of the first multiplexer 60a. The input <NUM> of the amplifier <NUM> receives the voltage appearing across the third temperature sensor 16a, the amplifier <NUM> amplifies the voltage, and then provides the amplified voltage to the input <NUM> of the analog to digital converter <NUM>. The controller <NUM> instructs the analog to digital converter <NUM> to digitize the resulting voltage. The controller <NUM> obtains the digitized resulting voltage reading from the analog to digital converter <NUM> and temporarily stores the digitized resulting voltage reading (which corresponds to the third temperature sensor 16a) in a buffer and the digitized resulting voltage reading is used to determine a temperature reading based on the digitized resulting voltage reading. The digitized resulting voltage reading may be referred to herein as a first electrical reading. The procedure may be repeated, sequentially, for each of the temperature sensors <NUM> (i.e. 16a-i) with conductors <NUM> (i.e. 30a-f) within the sensor array 90a. For example, to obtain a reading from the temperature sensor 16b, the controller <NUM> sends one or more commands to the first multiplexer 60a and the second multiplexer 60b to select the at least two conductors 30b and 30d both of which are in communication with the temperature sensor 16b, and configures the current source <NUM> to generate a known current to the at least two conductors 30b and 30d. The known current from the current source <NUM> is configured to flow through the first multiplexer 60a into the temperature sensor 16b via the conductor 30b and to the second multiplexer 60b via the conductor 30d resulting in a voltage appearing across that temperature sensor 16b and at the output 62a of the first multiplexer 60a. The input <NUM> of the amplifier <NUM> receives the voltage appearing across the temperature sensor 16b, the amplifier <NUM> amplifies the voltage, and then provides the amplified voltage to the input <NUM> of the analog to digital converter <NUM>. The controller <NUM> instructs the analog to digital converter <NUM> to digitize the resulting voltage. The controller <NUM> obtains the digitized resulting voltage reading from the analog to digital converter <NUM> and temporarily stores the digitized resulting voltage reading (which corresponds to the third temperature sensor 16a) in a buffer and the digitized resulting voltage reading is used to determine a temperature reading based on the digitized resulting voltage reading. The digitized resulting voltage reading from the temperature sensor 16b may be referred to herein as a second electrical reading. Similarly, to obtain a reading from the temperature sensor <NUM>, the controller <NUM> sends one or more commands to the first multiplexer 60a and the second multiplexer 60b to select the at least two conductors 30b and 30f in communication with the temperature sensor <NUM>, and configures the current source <NUM> to generate a known current. The known current from the current source <NUM> is configured to flow through the first multiplexer 60a into the temperature sensor <NUM> via the conductor 30b and to the second multiplexer 60b via the conductor 30f resulting in a voltage appearing across that temperature sensor <NUM> and at the output 62a of the multiplexer 60a. The controller <NUM> may pass the first temperature reading and/or the second temperature reading to the controller <NUM> within the hub <NUM>, and the controller <NUM> may communicate with the field generator <NUM> to adjust the alternating current waveform based on the first temperature reading and/or the second temperature reading.

It should be understood that additional conductors <NUM> may be used to increase the number of temperature sensors <NUM> within the sensor array <NUM>. For example, <FIG> illustrates another exemplary embodiment of a sensor array 90b having thirteen temperature sensors 16a-<NUM> connected to conductors 30a-<NUM>. Selective activation of at least two predetermined conductors <NUM> may result in a voltage appearing across at least one temperature sensor <NUM> connected to the at least two conductors <NUM> resulting in the temperature reading as described herein. <FIG> illustrates another exemplary embodiment of a sensor array 90c having twenty temperature sensors 16a-16t connected to conductors 30a-30i. Selective activation of at least two conductors <NUM> may result in a voltage appearing across the temperature sensor <NUM> connected to the at least two conductors <NUM> resulting in the temperature reading as described herein.

<FIG> illustrates another exemplary embodiment of a sensor array 90d that includes a reduced number of conductors <NUM> (30a-d) relative to the embodiments of <FIG> including a plurality of electronic switches <NUM> (92a-h), such as diodes configured to provide selective activation of one temperature sensor <NUM> (<FIG> shows 16a-h) when more than one temperature sensor <NUM> are connected to two conductors <NUM>. In one embodiment, the selection of the temperature sensor <NUM> can be accomplished by providing a particular polarity of voltage across the two conductors <NUM>. Generally, by providing a positive polarity or a negative polarity to a combination of conductors <NUM>, particular temperature sensors <NUM> may be activated. For example, two temperature sensors <NUM> and <NUM> are connected in circuit with the two conductors 30b and 30d, and two electronic switches <NUM> and <NUM>. The electronic switch <NUM> is in series with the temperature sensor <NUM>; and the electronic switch <NUM> is in series with the temperature sensor <NUM>. The electronic switch <NUM> is configured to conduct based upon a negative polarity, and the electronic switch <NUM> is configured to conduct based upon a positive polarity. By applying a positive polarity across conductors 30b and 30d, temperature sensor <NUM> may be activated (and temperature sensor <NUM> is not activated) providing a temperature reading. By applying a negative polarity across the same conductors 30b and 30d, temperature sensor <NUM> may be activated (and temperature sensor <NUM> not activated) providing a temperature reading.

Referring to <FIG>, in some embodiments, a conventional voltage divider approach for interfacing with the one or more temperature sensors <NUM> may be used. In some embodiments, additional readings may be obtained and used for self-calibration to increase the accuracy and/or precision of the temperature readings obtained from the one or more temperature sensors <NUM>. For example, in <FIG>, at least one input 64c of the first multiplexer 60a is connected to ground, and at least one input 64d of the first multiplexer 60a is connected to a precision resistor <NUM>. The controller <NUM> may temporarily store the digitized readings from the precision resistor <NUM> and the grounded input 64c in a buffer and/or any memory configured to store data. These additional readings may ultimately be used to calibrate the readings that were obtained from the one or more temperature sensors <NUM>. In some embodiments, such calibration may be implemented via the controller <NUM>. In some embodiments, calibration may occur prior to transmission of the digital data that corresponds to the temperature readings. In some embodiments, calibration may be implemented in a downstream processor (e.g., the controller <NUM> in the hub <NUM>) such that the digital data corresponding to the precision resistor <NUM> (and optionally the grounded input <NUM>) may be transmitted to a downstream processor, in addition to, any uncalibrated temperature readings obtained from the one or more temperature sensor <NUM>.

In some embodiments, calibration using the precision resistor <NUM> may compare the actual voltage measured across the precision resistor <NUM> with an expected voltage based on Ohm's law, the known value of the precision resistor <NUM>, and the expected value of the current being produced by the current source <NUM>. Deviations between the actual measured voltage and the expected voltage may be used to determine subsequent measurements (e.g., use as a multiplier) from the one or more temperature sensors <NUM>.

In some embodiments, the controller <NUM> in the distal circuit <NUM> may be configured to communicate with the hub <NUM> via universal asynchronous receiver-transmitter (UART) <NUM>, and transmit the temperature readings obtained from the one or more temperature sensors <NUM> to the hub <NUM>. In some embodiments, the controller <NUM> may be a processor programmed to operate autonomously and configured to automatically collect temperature readings from each of the one or more temperature sensors <NUM>, storing the result in a buffer as described above, and subsequently transmitting contents of the buffer (i.e., readings for each of the temperature sensors <NUM>, and optionally the additional readings described herein) to the hub <NUM>.

In some embodiments, the controller <NUM> may be a processor programmed to operate as a slave to a master controller located in the hub <NUM>. For example, the controller <NUM> may begin in a quiescent state, wherein the controller <NUM> solely monitors incoming commands from the master controller that arrive via the UART <NUM>. Examples of commands that can arrive from the master controller may include, but are not limited to, "collect samples" command, "send data" command, and/or the like. When the controller <NUM> recognizes that a "collect samples" command has arrived, the controller <NUM> may be configured to initiate the method described herein to obtain one or more temperature readings from the one or more temperature sensors <NUM>, and store results in the buffer and/or any memory configured to store data. In another example, the controller <NUM> may recognize a "send data" command, and execute a method to transmit previously collected temperature readings from the buffer and/or memory to the hub <NUM> via the UART <NUM>.

In some embodiments, temperature measurements may be synchronized. For example, the controller <NUM> in the hub <NUM> may send a "collect samples" command to one or more controllers <NUM> in the distal circuit <NUM> either simultaneously or in rapid succession, such that the temperature readings obtained from each of the transducer arrays <NUM> may be obtained at or near the same time. In some embodiments, the temperature readings may be collected by the hub <NUM> in one or more batches of each controller <NUM>.

Most systems that use TTFields to treat tumors switch the direction of the field that is being applied to the tumor periodically (e.g., every second). To minimize noise in the temperature measurements, a small time gap during which the field is not applied in either direction may be introduced, and the temperature measurements can be made during the time gap. In some embodiments, the controller <NUM> located in the hub <NUM> may synchronize timing of the "collect samples" command to all controllers <NUM> such that each of the distal circuits <NUM> may obtain temperature readings during the time gap. The temperature readings simultaneously obtained from each transducer array <NUM> may minimize duration of the time gap. For example, if the system <NUM> requires <NUM> to obtain a single measurement, taking thirty-six measurements in sequence (i.e., four distal circuits × nine temperature sensors <NUM> at each distal circuit <NUM>, for example) may take <NUM>. In contrast, if each of four distal circuits <NUM> operates in parallel, each distal circuit <NUM> can obtain <NUM> samples in <NUM>, such that <NUM> samples can be obtained in <NUM>. It should be noted that the "send data" command may not be sensitive to noise such that the "send data" command can be executed while the fields remain on, and as such, is not time-critical.

In some embodiments, some or all of the following components may be implemented by a single integrated circuit: first multiplexer 60a, second multiplexer 60b, amplifier <NUM>, analog to digital converter <NUM>, controller <NUM>, UART <NUM>, and current source <NUM>. One example of a single integrated circuit that includes all of these functional blocks is the Cypress CY8C4124LQI-443T programmable system on chip (PSoC), manufactured by Cypress Semiconductor Corp. , having a principal place of business in San Jose, CA.

Embodiments illustrated under any heading or in any portion of the disclosure may be combined with embodiments illustrated under the same or any other heading or other portion of the disclosure. Any combination of the elements described herein in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claim 1:
An apparatus for imposing electric fields through a target region in a body of a patient, the apparatus comprising:
at least one transducer array (<NUM>) having a plurality of electrode elements (<NUM>) configured for placement on the body of the patient, the plurality of electrode elements (<NUM>) being configured to provide tumor treating fields (TTFields) via an alternating current waveform; and
a sensor array (<NUM>; 90a; 90b; 90c; 90d) having at least one first temperature sensor (<NUM>; 16a; 16a, b) and at least one second temperature sensor (<NUM>; 16d; 16e; 16f; 16e, f);
characterized by:
the at least one first temperature sensor (<NUM>; 16a; 16a, b) being connected to first and second conductors (<NUM>; 30a, d; 30a, e; 30a, f; 30a, c) and the at least one second temperature sensor (<NUM>; 16d; 16e; 16f; 16e, f) being connected to the first conductor (<NUM>; 30a) and a third conductor (<NUM>; 30e; 30f; <NUM>; 30d); and
a controller (<NUM>) configured to:
provide a first known amount of electricity for activation of the at least one first temperature sensor (<NUM>; 16a; 16a, b) via the first and second conductors (<NUM>; 30a, d; 30a, e; 30a, f; 30a, c) and a second known amount of electricity for activation of the at least one second temperature sensor (<NUM>; 16d; 16e; 16f; 16e, f) via the first and third conductors (<NUM>; 30a, e; 30a, f; 30a, g; 30a, d);
obtain a first electrical reading induced by the first known amount of electricity and a second electrical reading induced by the second known amount of electricity;
determine a first temperature reading based on the first electrical reading and a second temperature reading based on the second electrical reading; and
adjust the alternating current waveform based on the first and second temperature readings.