Reducing electrosensation whilst treating a subject using alternating electric fields by pairing transducer arrays together
When treating a subject using alternating electric fields (e.g., using TTFields to treat a tumor, or using alternating electric fields to increase the permeability of the blood brain barrier), some subjects experience an unpleasant electrosensation effect. This electrosensation can be reduced or eliminated by increasing the area of the transducer arrays that is active during certain times in the treatment. In some embodiments, this is accomplished by applying an AC signal between two pairs of transducer arrays at certain times (as opposed to the prior art approach of applying an AC signal between two individual transducer arrays).
1 . An apparatus for treating a tumor in a target region and promoting delivery of a substance across a biological barrier in the target region, the apparatus comprising:
at least one signal generator configured to generate an alternating voltage at a first frequency and to generate an alternating voltage at a second frequency, wherein the second frequency is lower than the first frequency;
a bank of switches having at least one control input, a first output terminal, a second output terminal, a third output terminal, and a fourth output terminal,
wherein the bank of switches inputs the alternating voltage at the first frequency,
wherein the bank of switches inputs the alternating voltage at the second frequency,
wherein the bank of switches is configured to, in response to a first state of the at least one control input, route the alternating voltage at the first frequency so that the alternating voltage at the first frequency appears between the first output terminal and the second output terminal,
wherein the bank of switches is configured to, in response to a second state of the at least one control input, route the alternating voltage at the first frequency so that the alternating voltage at the first frequency appears between the third output terminal and the fourth output terminal, and
wherein the bank of switches is configured to, in response to a third state of the at least one control input, route the alternating voltage at the second frequency so that the alternating voltage at the second frequency appears between (a) both the first output terminal and the third output terminal and (b) both the second output terminal and the fourth output terminal; and
a controller programmed to, at different intervals of times, (i) set the at least one control input to the first state, (ii) set the at least one control input to the second state, and (iii) set the at least one control input to the third state.
2 . The apparatus of claim 1 , wherein the first frequency is selected to provide an anti-mitotic effect, and
wherein the second frequency is selected to increase a permeability of a biological barrier.
3 . The apparatus of claim 1 , wherein the first frequency is between 50 kHz and 1 MHz, and wherein the second frequency is between 50 kHz and 300 kHz.
4 . The apparatus of claim 1 , wherein the controller is programmed to (i) set the at least one control input to the first state and (ii) set the at least one control input to the second state in an alternating sequence at least 10,000 times.
5 . The apparatus of claim 1 , wherein the controller is programmed to, after repeating (i) and (ii) at least 10,000 times, set the at least one control input to the third state and subsequently leave the at least one control input in the third state for at least 12 hours.