Sensing system and method of operation

A method of operating a sensing system, wherein the sensing system comprises:

• (i) an electrowetting device, which electrowetting device comprises:
• an array of actuation electrodes,
• an insulator layer covering the actuation electrodes and having an outermost hydrophobic surface;
• a first sensing electrode;
• and
• a second sensing electrode;
• (ii) disposed on the hydrophobic surface,
• an apolar fluid medium,
• a first, second and third droplet comprising a polar liquid medium,
• the first and/or the second and/or the third droplet comprises a layer of amphipathic molecules at an interface between said first and/or second and/or third droplet and the apolar fluid medium;
• the first droplet is in contact with the second droplet via a droplet interface and with the third droplet via a droplet interface;
• each droplet interface comprises a layer of amphipathic molecules;
• at least the interface between the first droplet and the second droplet comprises a transmembrane pore;
• the first droplet comprises an analyte;
• each of the second and the third droplets comprises an electron mediator;
• and
• the second and third droplets are in electrical contact with the second sensing electrode and the first sensing electrode respectively;
• (iii) a control system configured to obtain an electrical measurement from the first and second sensing electrodes, and to apply an actuation signal to the array of actuation electrodes;
• wherein the method comprises
• a) obtaining an electrical measurement from the first and second sensing electrodes;
• b) analysing the electrical measurement and then selecting a droplet operation based on the electrical measurement according to one or more instructions stored in the control system;
• and
• c) applying an actuation signal to an actuation electrode to effect the droplet operation;
• wherein the droplet operation comprises moving the first droplet to separate the first droplet from the second and/or third droplets, or moving the second and/or third droplets to separate the second and/or third droplets from the first droplet.

A method of operating a sensing system, wherein the sensing system comprises:

• (i) an electrowetting device, which electrowetting device comprises:
• an array of actuation electrodes, and
• an insulator layer covering the actuation electrodes and having an outermost hydrophobic surface;
• a first sensing electrode;
• and
• a second sensing electrode;
• (ii) disposed on the hydrophobic surface:
• an apolar fluid medium,
• a first, second and optionally a third droplet comprising a polar liquid in the apolar fluid medium;
• the first and/or the second droplet comprises a layer of amphipathic molecules at an interface between said first and/or second droplet and the apolar fluid medium;
• the first droplet is in contact with the second droplet via a droplet interface, or the third and second droplets are each in contact with the first droplet via a droplet interface;
• each droplet interface comprises a layer of amphipathic molecules;
• at least one of the droplet interfaces comprises a transmembrane pore;
• the first droplet comprises an analyte;
• one of the first and the second droplets comprises an electron mediator;
• the first or where present optionally the third droplet is in electrical contact with the first sensing electrode;
• and
• the second droplet is in electrical contact with the second sensing electrode;
• (iii) a control system configured to obtain an electrical measurement from the first and second sensing electrodes, and to apply an actuation signal to the array of actuation electrodes;
• and wherein the method comprises
• a) obtaining an electrical measurement from the first and second electrodes, and repeating this step a plurality of times to obtain a plurality of electrical measurements;
• b) comparing one or more of the electrical measurements with one or more of the other electrical measurements among the plurality of electrical measurements, determining an alteration in the electrical measurement detected over time that is attributable to a loss of electron mediator in the droplet, optionally in the second droplet, and selecting a droplet operation to increase the concentration of electron mediator in that droplet, optionally in the second droplet;
• and
• c) applying an actuation signal to an actuation electrode to effect the droplet operation.

A method of operating a sensing system wherein the sensing system comprises

• (i) an electrowetting device, which electrowetting device comprises:
• an array of actuation electrodes;
• an insulator layer covering the actuation electrodes and having an outermost hydrophobic surface;
• a first sensing electrode;
• and
• a second sensing electrode;
• (ii) disposed on the hydrophobic surface of the electrowetting device:
• an apolar fluid medium;
• a first, second and third droplet comprising a polar liquid medium;
• the first and/or the second and/or the third droplet comprise a layer of amphipathic molecules at an interface between said first and/or second and/or third droplet and the apolar fluid medium;
• the first droplet being in contact with the second droplet via a droplet interface, said droplet interface comprising a layer of amphipathic molecules and a first transmembrane pore;
• the third droplet being in contact with the first or second droplet via another droplet interface, said another droplet interface comprising a layer of amphipathic molecules and a second transmembrane pore;
• and
• the first droplet comprising an analyte;
• (iii) a control system configured to obtain an electrical measurement from the first and second sensing electrodes, and to apply an actuation signal to the array of actuation electrodes;
• wherein the method comprises
• a) obtaining an electrical measurement from the first and second sensing electrodes;
• b) analysing the electrical measurement and then selecting a droplet operation based on the electrical measurement according to one or more instructions stored in the control system;
• and
• c) applying an actuation signal to an actuation electrode to effect the droplet operation.

A method of operating a sensing system, wherein the sensing system comprises:

• (i) an electrowetting device, which electrowetting device comprises:
• an array of actuation electrodes, and
• an insulator layer covering the actuation electrodes and having an outermost hydrophobic surface;
• a first sensing electrode;
• and
• a second sensing electrode;
• (ii) disposed on the hydrophobic surface:
• an apolar fluid medium,
• first, second, third and fourth droplets each comprising a polar liquid in the apolar fluid medium;
• the first, second, third and/or fourth droplet comprises a layer of amphipathic molecules at an interface between said first, second, third and/or fourth droplet and the apolar fluid medium;
• the third droplet is in contact with the first droplet via a droplet interface, the first droplet is in contact with the second droplet via another droplet interface, and the second droplet is in contact with the fourth droplet via yet another droplet interface;
• each droplet interface comprises a layer of amphipathic molecules;
• the droplet interface between the first and second droplets comprises a first transmembrane pore;
• the droplet interface between the first and third droplets comprises a plurality of further transmembrane pores which are ion channels;
• the droplet interface between the second and fourth droplets also comprises a plurality of further transmembrane pores which are ion channels;
• the first droplet comprises an analyte;
• the third and fourth droplets comprise an electron mediator;
• the third droplet is in electrical contact with the first sensing electrode;
• and
• the fourth droplet is in electrical contact with the second sensing electrode;
• (iii) a control system configured to obtain an electrical measurement from the first and second sensing electrodes, and to apply an actuation signal to the array of actuation electrodes;
• wherein the method comprises
• a) obtaining an electrical measurement from the first and second electrodes, and repeating this step a plurality of times to obtain a plurality of electrical measurements;
• b) comparing one or more of the electrical measurements with one or more of the other electrical measurements among the plurality of electrical measurements, determining an alteration in the electrical measurement detected over time that is attributable to a loss of electron mediator in the third or fourth droplet and selecting a droplet operation to increase the concentration of electron mediator in that droplet;
• and
• c) applying an actuation signal to an actuation electrode to effect the droplet operation.