Period-to-period analysis of ac signals from nanopore sequencing

A method of using a sequencing cell, the method comprising:

• applying an alternating signal across a nanopore of the sequencing cell, the nanopore configured to receive a tag that is connected to a nucleotide, thereby creating a threading event, each cycle of the alternating signal comprising a first portion and a second portion, wherein voltage levels of the second portion are opposite of a reference voltage than voltage levels of the first portion;
• acquiring a first set of voltage data during the first portion of a plurality of cycles of the alternating signal, wherein each data point of the first set of voltage data corresponds to a value of a resistance of the nanopore at a different time, where the resistance of the nanopore changes when the tag is received within the nanopore;
• determining a shifted set of voltage data from the first set of voltage data, wherein each cycle of data points of the first set of voltage data and the shifted set of voltage data includes a specified number of data points;
• computing difference data by computing differences between data points of the first set of voltage data and corresponding data points of the shifted set of voltage data;
• and
• identifying the threading event based on one or more data points in the difference data.

A non-transitory computer-readable storage medium storing computer-executable instructions that, when executed by a processor, cause a sequencing cell to perform operations comprising:

• applying an alternating signal across a nanopore of the sequencing cell, the nanopore configured to receive a tag that is connected to a nucleotide, thereby creating a threading event, each cycle of the alternating signal comprising a first portion and a second portion, wherein a voltage level of the second portion is opposite of a reference voltage than a voltage level of the first portion;
• acquiring a first set of voltage data during the first portion of a plurality of cycles of the alternating signal, wherein each data point of the first set of voltage data corresponds to a value of a resistance of the nanopore at a different time, where the resistance of the nanopore changes when the tag is received within the nanopore;
• determining a shifted set of voltage data from the first set of voltage data, wherein each cycle of data points of the first set of voltage data and the shifted set of voltage data includes a specified number of data points;
• computing difference data by computing differences between data points of the first set of voltage data and corresponding data points of the shifted set of voltage data;
• and
• identifying the threading event based on one or more data points in the difference data.