Microparticle sorting apparatus and delay time determination method
A microparticle sorting apparatus includes a detection unit which detects microparticles flowing through a flow path; an imaging device which images a droplet containing the microparticles which is discharged from an orifice provided on an edge portion of the flow path; a charge unit which applies a charge to the droplets; and a control unit which determines a delay time as from a time that the microparticles are detected by the detection unit to the time at which a number of bright spots in a standard region, which is set beforehand, of image information imaged by the imaging device reaches the maximum, making it possible for the charge unit to apply a charge to the microparticles once the delay time has lapsed after the microparticles are detected by the detection unit.
1. A microparticle sorting apparatus comprising:
a detector configured to detect microparticles flowing through a flow path;
an imaging device configured to obtain a plurality of images of a droplet containing at least one of the microparticles, wherein the droplet is discharged from an orifice provided on an edge portion of the flow path; and
a controller configured to:
control the imaging device to obtain the plurality of images, the plurality of images having a standard region in respective images of the plurality of images;
determine a delay time by examining the standard region in respective images of the plurality of images and identifying an image of the plurality of images that has a maximum brightness characteristic within the standard region; and
set a timing for applying charge to droplets based on the delay time.
2. The microparticle sorting apparatus according to claim 1 ,
wherein the controller is configured to determine a the delay time by comparing a brightness characteristic in at least one comparison region to a brightness characteristic in the standard region for an image of the plurality of images, wherein the at least one comparison region is adjacent to the standard region along a discharge direction of the droplets in the image.
3. The microparticle sorting apparatus according to claim 2 ,
wherein the at least two comparison regions includes a first comparison region and a second comparison region are arranged on opposite sides of the standard region, and
wherein the controller is configured to determine the delay time based on a brightness characteristic in the first comparison region and a brightness characteristic in the second comparison region.
4. The microparticle sorting apparatus according to claim 3 ,
wherein the controller is further configured to
calculate a first time at which a brightness characteristic of the first comparison region reaches a predetermined percentage of a maximum value,
calculate a second time at which a brightness characteristic of the second region reaches a predetermined percentage of a maximum value, and
determine a time for the standard region as (the first time+the second time)/2.
5. The microparticle sorting apparatus according to claim 3 ,
wherein the controller is configured to adjust a discharge frequency of the droplets based on the delay time, and determine an optimal discharge frequency of the droplets to be the discharge frequency at which a point where the droplets are formed is proximate the orifice.
6. The microparticle sorting apparatus according to claim 1 , further comprising:
a pair of deflection plates disposed opposite one another to interpose the droplets imaged by the imaging device, which change a progression direction of the droplets using an electrical force which acts between the deflection plates and the charge.
7. The microparticle sorting apparatus according to claim 1 ,
wherein the microparticle sorting apparatus is a microchip-type flow cytometer in which the orifice and the flow path are provided in the microchip.
8. The microparticle sorting apparatus according to claim 1 ,
wherein the controller is further configured to control the imaging device to obtain the plurality of images based on a time when one of the microparticles is detected by the detector.