Methods of sperm cell sensing utilizing an avalanche photodiode and cytometer apparatus
Inventors
SAVAGE, Frederick • Szejna, Glenn J. • Xia, Zheng
Assignees
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Publication Number
US-11600736-B2
Publication Date
2023-03-07
Expiration Date
Abstract
A cytometer includes an avalanche photodiode, a switching power supply, a filter, and voltage adjustment circuitry. The switching power supply includes a feedback loop. The filter is electrically connected between the switching power supply and the avalanche photodiode. The voltage adjustment circuitry adjusts a voltage on the feedback loop based at least in part on a voltage measured between the filter and the avalanche photodiode.
Core Innovation
The disclosed flow cytometry system uses an electromagnetic radiation source to emit an interrogation beam at a particle in an interrogation location, and uses avalanche photodiode circuitry to detect emissions from the particle at the interrogation location. The avalanche photodiode outputs a signal based on the detected emission, and that output signal is used to charge droplets differentially.
A set of charge plates deflects the differentially charged droplets based on the avalanche photodiode output signal, enabling particle sorting in the flow cytometry apparatus. The system detects fluorescence produced by illuminating labeled particles with the interrogation beam and converting the detected emission into an analog intensity signal for digitization and processor analysis.
In the sperm-focused embodiment, DNA is stained in a nucleus of a sperm cell, irradiated, and fluorescent light emitted from the irradiated and stained DNA is detected using an avalanche photodiode. Based on the detected emission, differentially charged droplets are charged and then deflected with charge plates for droplet-based separation, and downstream actions can include determining sperm sex from the DNA amount and using that determination to differentiate/sort sperm populations.
The document also describes circuitry associated with avalanche photodiode operation, including a switching DC/DC power supply with a feedback loop and a filter network between the supply and the avalanche photodiode. Voltage adjustment circuitry measures the voltage between the filter and the avalanche photodiode and adjusts feedback voltage, including use of temperature sensing and avalanche photodiode device characteristics, with digital control using an ADC/DAC arrangement.
Claims Coverage
The provided independent claims are directed to three inventive features: a flow cytometry particle-sorting system, a method for assessing DNA in a sperm nucleus, and a method for causing deactivation of particles, each using avalanche photodiode detection followed by droplet charging and charge-plate deflection.
Avalanche photodiode-based emission detection
The system includes avalanche photodiode circuitry comprising at least one avalanche photodiode configured to detect an emission of electromagnetic radiation by the particle at the interrogation location and output a signal based on the detected emission.
Differential droplet charging from photodiode output
A set of charge plates deflect differentially charged droplets, wherein the differentially charged droplets are charged based on the output signal of the avalanche photodiode.
DNA amount assessment in a sperm nucleus
The method assesses an amount of DNA within a nucleus of a sperm cell by staining the DNA within the nucleus, irradiating the stained DNA within the nucleus, and detecting, with an avalanche photodiode, fluorescent light emitted from the irradiated and stained DNA within the nucleus.
Droplet-based deflection using avalanche photodiode signal
The method charges differentially charged droplets with an output signal of the avalanche photodiode and deflects the differentially charged droplets with a set of charge plates.
Deactivation using interrogation-beam detection and droplet deflection
The method causes the deactivation of particles by emitting an interrogation beam directed at a particle in an interrogation location, detecting by an avalanche photodiode an emission of electromagnetic radiation by the particle, outputting an output signal based on the detected emission, and deflecting differentially charged droplets with a set of charge plates, wherein the differentially charged droplets are charged based on the output signal of the avalanche photodiode.
Across the independent claims, the core coverage is the use of avalanche photodiode detection of interrogation-induced emissions, including fluorescence from stained DNA in sperm nuclei, to generate an output signal that is used to differentially charge droplets, followed by charge-plate deflection, with an additional deactivation-focused method variant.
Stated Advantages
Documented Applications
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