CELL DETECTOR AND CELL DETECTION METHOD

A cell detector and a cell detection method detect cell proliferation. A cell detector includes a light emitter, a culture vessel that accommodates a culture medium containing a cell, a first slit member including a first slit and a first light shield, and at least one light receiver that receives light emitted from the light emitter and passing through the culture medium and the first slit in the first slit member in an order of the culture medium and the first slit. The first light shield in the first slit member blocks light emitted from the light emitter and scattered by the cell in the culture vessel when the cell is at a position overlapping the first slit.

FIELD

The present disclosure relates to a cell detector and a cell detection method for detecting cell proliferation.

BACKGROUND

In cell culture, the state of cells and the increase in cell number are visually observed using a phase-contrast microscope (refer to, for example, Patent Literatures 1 to 3). Another known technique uses a direct-contact complementary metal-oxide-semiconductor (CMOS) sensor to image cells for observation of their proliferation (refer to, for example, Patent Literature 4).

CITATION LIST

Patent Literature

BRIEF SUMMARY

Technical Problem

However, the known techniques described in Patent Literatures 1 to 3 involve lengthy visual observation of cells. Culture of a large number of cells with these techniques can place a large burden on the operator and increase the operation time. The observation using the CMOS sensor with the known technique in Patent Literature 4 is suitable for detailed observation of cells, such as observation of their shapes. However, the technique provides local information alone and is not suitable for determining, for example, the rough number of cells in the entire well. In addition, the techniques in Patent Literatures 1 to 4 each use expensive equipment and involve high facility costs.

The development in bioengineering may allow industrialized cell culture, which expects efficient culture of cells on a larger scale.

Inexpensive cell detectors and cell proliferation methods that can easily and efficiently detect cell proliferation are thus awaited.

Solution to Problem

A cell detector according to an embodiment of the present disclosure includes a light emitter, a culture vessel that accommodates a culture medium containing a cell, a first slit member including a first slit and a first light shield, and at least one light receiver that receives light emitted from the light emitter and passing through the culture medium and the first slit in an order of the culture medium and the first slit. The first light shield in the first slit member blocks light emitted from the light emitter and scattered by the cell in the culture vessel when the cell is at a position overlapping the first slit.

A cell detection method according to an embodiment of the present disclosure is a cell detection method implementable with the above cell detector. The method includes placing the culture medium and the cell in the culture vessel, culturing the cell, illuminating the culture medium containing the cell with light emitted from the light emitter, and obtaining an amount of light passing through the first slit member and received by the light receiver, or an amount of light passing through the first slit member and the second slit member and received by the light receiver.

Advantageous Effects

The cell detector according to an embodiment of the present disclosure includes the first slit member including the first slit and the first light shield. The first light shield in the first slit member blocks light emitted from the light emitter and scattered by the cell in the culture vessel. When the cell is included in a portion of the culture medium corresponding to the first slit in the first slit member, the intensity of the light received by the light receiver (the current value generated in response to the received light, or more specifically, the current value resulting from photoelectric conversion, expressed as Ip1) is lower than the intensity of the light received by the light receiver when no cell is included in the portion (the current value resulting from photoelectric conversion, expressed as Ip0), or in other words, Ip1<Ip0. This is because no scattered light component is received by the light receiver when the cell is included in the portion. This structure allows reliable detection of the cell in the portion of the culture medium corresponding to the first slit. For the cell remaining stationary, the intensity of the light received by the light receiver decreases from Ip0 initially to Ip1 over time, and decreases further as the cell proliferates two- or three-dimensionally. This allows substantially accurate estimation of the number of cells included in the entire culture medium. For the cell moving, the probability of the cell included in the portion of the culture medium corresponding to the first slit may be measured per unit time, for example, per minute or per hour (presence time per unit time). In another example, the number of cells crossing the portion of the culture medium corresponding to the first slit may be measured per unit of time. Based on these measurements, the number of cells included in the entire culture medium can be estimated substantially accurately.

The cell detector according to an embodiment of the present disclosure includes the first slit member including a plurality of first slits. This structure allows more precise measurement by averaging the detected values for the plurality of first slits. This allows more accurate estimation of the number of cells included in the entire culture medium.

The cell detector according to an embodiment of the present disclosure includes the light receiver located between the bottom surface of the first slit member and the bottom surface of the culture vessel. The first slit member and the light receiver may be integrated into a detection substrate that is accommodated in the culture vessel. When the number of proliferated cells exceeds a predetermined number, the detection substrate can be removed from the culture vessel and disposed of.

The cell detector according to an embodiment of the present disclosure further includes a second slit member including a second slit and a second light shield between the first slit member and the light receiver. The scattered light is blocked by the first slit member and the second slit member. This allows more effective blocking of the scattered light. This structure allows reliable detection of the cell in the portion of the culture medium corresponding to the first slit and the second slit.

The cell detector and the cell detection method according to one or more embodiments of the present disclosure with the above structure can easily detect cell proliferation at low costs. In addition, the cell detector according to an embodiment can be mass-produced at low costs and thus be disposable. The disposable cell detector can prevent contaminants from entering the culture medium.

DETAILED DESCRIPTION

A cell detector according to one or more embodiments of the present disclosure will now be described with reference to the drawings.

Detector

First Embodiment

FIG. 1is a schematic view of a cell detector100according to a first embodiment.

The cell detector100according to the first embodiment includes a light emitter10, a first slit member20including first slits90and first light shields95, light receivers30that receive light emitted from the light emitter10and passes through a culture medium containing cells and the first slits90in the first slit member20in the stated order, and a culture vessel40for culturing cells.

A culture medium70(hereafter, also a culture substrate or cell culture medium) provides a growth environment for target cells in cell culture. The culture medium70is a source of nutrients such as a carbon source including glucose, a nitrogen source including peptone and ammonium sulfate, and inorganic salts including amino acids, vitamins, and phosphate. The culture medium70also provides a scaffold (platform) for cell proliferation. More specifically, the culture medium70may be a liquid medium or a solid medium. The liquid medium includes a liquid containing the above nutrients used for cell culture. The solid medium includes the liquid that is then solidified by adding agar or gelatin. The cell detector100according to the present embodiment may use a light-transmissive liquid medium allowing the cells to move in a plane (two-dimensionally) crossing the first slits90. In some embodiments, the cell detector100may include a light-transmissive solid medium allowing the cells to slightly move two-dimensionally or to proliferate three-dimensionally above and overlapping the first slits90.

The first light shields95in the first slit member20blocks light emitted from the light emitter10and scattered by cells60in the culture vessel40. The scattered light includes a component reflected and scattered at the surfaces of the cells and a component transmitted through the cells and refracted at cell membranes. More specifically, scattered light corresponds to light incident on the main surface of the first slit member20substantially perpendicularly and is redirected by the cells. Arrows L (solid lines) in the figure indicate the path of light emitted from the light emitter10, arrows LS1(dashed lines) indicate the path of light transmitted straight through the cells60, and arrows LS2(dashed lines) indicate the path of light transmitted through and scattered by the cells60.

FIG. 2is a block diagram of the cell detector100according to the first embodiment. The cell detector100according to the present embodiment includes the light emitter10, the first slit member20, the light receivers30, the culture vessel40, and a determiner50. The determiner50determines that the cells60have undergone sufficient proliferation. The light emitter10, the light receivers30, and the determiner50are electrically connected to one another. The determiner50may be implemented with, for example, a central processing unit (CPU).

The determiner50may be eliminated in the present embodiment when the detection results can be output from the light receivers30to an external device. For example, the detection results may be displayed on an image display device (a display) included in an external personal computer. The electrical connection between the light receivers30and the determiner50may be a wired connection using a signal cable or a wireless connection using a transmitter and receiver and an antenna.

The light emitter10illuminates the cells60in the culture vessel40with light. The light emitter10may be, for example, a light-emitting device such as a light-emitting diode (LED), an electroluminescence device (EL device), a fluorescent lamp, or a laser light emitter such as a semiconductor laser element. The light emitter10faces the light receivers30with the first slit member20between them. The first slits90in the first slit member20and the light receivers30may overlap each other in a plan view. In this case, the light receivers30can receive light passing through the first slits90with high sensitivity. In addition, the difference (Ip0−Ip1) between the intensity of the light received by the light receivers30when the cells60are included in portions of the culture medium70corresponding to the first slits90in the first slit member20(a current value resulting from photoelectric conversion, expressed as Ip1) and the intensity of the light received by the light receivers30when no cells60are included in the portions (a current value resulting from photoelectric conversion, expressed as Ip0) can be greater.

The first slit member20causes light emitted from the light emitter10and scattered by the cells60in the culture vessel40to avoid reaching the light receivers30. The first light shields95in the first slit member20may be formed from, for example, a light-shielding material including a black metal layer such as a chromium (Cr) layer or a black resin layer (black matrix) located in a portion of the lower surface (the surface facing the light receivers30) of a transparent substrate excluding the first slits90. Examples of the transparent substrate include a glass substrate and a plastic substrate.

The first slit member20may include one first slit90alone or multiple first slits90. For the first slit member20including one first slit90, the first slit90may be, for example, cross-shaped, spiral-shaped, lattice-shaped, circular, elliptical, triangular, square, or rectangular in a plan view. The first slit90may have any shape as appropriate for the shape of the culture vessel40, and the shape, size, motility including movement velocity, and the proliferation characteristics of the cells60. For the first slit member20including multiple first slits90, the first slits90may be, for example, rectangular in a plan view.FIG. 3shows an example shape of the first slit90.

As shown inFIG. 3, the rectangular first slit90may have a dimension in the width (W) direction smaller than the diameter of the cell60and a dimension in the length (L) direction, which is orthogonal to the width direction, larger than the length of the cell60(diameter RL) in the length direction. In this case, the scattered light LS2(shown inFIG. 2) transmitted through, refracted, and scattered (redirected) by the cells60deviates from the path to each light receiver30in the length direction in a plan view while traveling toward the light receivers30. This prevents scattered light from passing through the first slits90in the first slit member20and being received by the light receivers30. For example, the rectangular first slit90may have a dimension of 7 to 25 μm in the width direction and a dimension of 25 to 1,000 μm in the length direction. More specifically, the first slit90may have a dimension of 25 to 50 μm in the length direction. The cells60may typically have curved peripheries, such as circular or elliptical peripheries in a plan view. The cell is circular in the example ofFIG. 3. However, the cells60may have any shape other than a circle.

The cells60may be of any type, including animal cells, plant cells, yeast cells, or bacterial cells. Animal cells include muscle cells, visceral cells such as the liver, blood cells such as lymphocytes, monocytes, and granulocytes, nerve cells, immune cells, and induced pluripotent stem (iPS) cells. These cells may be tissue-derived primary cells or may be subcultured cells. iPS cells have pluripotency and the self-renewal ability. iPS cells are produced by introducing several types of genes into somatic cells, such as skin cells of a human, and culturing the cells to be pluripotent cells that can differentiate into cells of various tissues and organs, similarly to embryonic stem (ES) cells. The self-renewal ability allows iPS cells to retain pluripotency after division and proliferation, thus achieving substantially unlimited proliferation. The cell detector100according to the present embodiment can be used to manage the number of proliferated iPS cells with high proliferative ability. The cells60may be prokaryotic cells such as anEscherichia colicell, or eukaryotic cells such as animal cells or plant cells. The cells60may be, for example, normal cells, abnormal cells such as tumor cells, or artificially created cells such as transgenic cells. The cells60may also be cultured as part of a living tissue. The cell culture may be adherent cell culture or suspension cell culture.

The first light shields95in the first slit member20may be formed from a light-shielding material in a portion of the upper surface (the surface facing the light emitter10) of the first slit member20excluding the first slits90. The light-shielding material may be, but not limited to, a black metal or a black resin such as a black resist.

The light receivers30receive light passing through the first slits90in the first slit member20without being transmitted through the cells60and light traveling straight after transmitted through the cells60. Each light receiver30may include, for example, a light receiving element such as a silicon photodiode. Photodiodes can be mass-produced at lower costs using thin-film technologies including thin-film transistors.

The first slit member20is located under the cells60and the light receivers30are located directly below the first slit member20. This structure allows detection of the scattering intensity of light scattered by the cells60using a difference in the light detection intensity, allowing detection of the cells60included in the portions of the culture medium70corresponding to the first slits90. Formula 1 represents the amount of light I1received by the light receivers30when no cells60are included in the portions of the culture medium70corresponding to the first slits90. Formula 2 represents the amount of light I1′ received by the light receivers30when the cells60are included in the portions of the culture medium70corresponding to the first slits90.

In these formulas, Jo is the amount of light emitted from the light emitter10, A is the amount of light absorbed by the cells60, B is the amount of light absorbed by the culture medium70, SL is the amount of light scattered by the cells60, and I1and I1′ are the amount of light received by the light receivers30. The term I0−(B+A) indicates the amount of light transmitted through the cell60and traveling straight without being scattered.

For the component transmitted through the cells60and traveling straight, the amount of light emitted from the light emitter10does not decrease substantially, except for the amount of light B absorbed by the culture medium70. This is because the cells60have a high transmittance and thus A is a low value. However, the cells60each have an inherent refractive index, and light transmitted through the cells60are scattered. The light receivers30receive no scattered light. The amount of light SL thus becomes larger as the number of cells60increases, and the amount of light received by the light receiver30decreases. The use of multiple first slits90allows more precise detection.

In other words, when proliferation of the cells60is insufficient in the early stage of cell culture, a small number of cells60are contained in the culture vessel40, causing a slight decrease of light resulting from scattering. Light emitted from the light emitter10is thus received by the light receivers30with almost no scattering. After sufficient proliferation of the cells60, a large number of cells60are densely contained in the culture vessel40, thus scattering most of the light emitted from the light emitter10transmitted through the cells60. A small amount of light is received by the light receiver30. For the cells60that have undergone sufficient proliferation in the culture vessel40, the amount of light received by the light receivers30corresponding to the number of proliferated cells60is measured in advance and stored as a predetermined amount into a storage table in, for example, a memory device. In response to an amount of light received by the light receivers30being smaller than or equal to the predetermined amount (greater than or equal to a predetermined number of proliferated cells), the cells60are determined to have proliferated to the predetermined number or greater. The predetermined number may be the number of cells per unit area, for example, per 1 mm2or per 1 cm2. In some embodiments, the predetermined number may be the number of cells per unit volume, for example, per 1 mm3or per 1 cm3. For example, the predetermined number may be about 1,000 to 100,000 per unit area or 100 to 100,000 per unit volume.

The determiner50determines that the cells60have proliferated to the predetermined number or greater in response to an amount of the light received by the light receivers30being smaller than or equal to the predetermined amount. The predetermined amount may be an amount determined in advance. For example, the predetermined amount may be the amount of light received by the light receivers30without being scattered by the cells60when the cells60have proliferated on the entire bottom surface of the culture vessel40or on the entire upper surface of the first slit member20. The predetermined number may be a number determined in advance. For example, the predetermined number may be the number of cells60densely covering the entire bottom surface of the culture vessel40or the entire upper surface of the first slit member20for which the culture medium is to be replaced. The sufficient proliferation of the cells60can be determined by determining whether the cells60are dense in the culture vessel40and the proliferation rate is decreased (whether the cells60have reached confluence).

The structure according to a modification of the present embodiment may include as many light receivers30as the first slits90. Each light receiver30may have dimensions in the width and length directions substantially equal to the dimensions of the first slit90in the width and length directions. Each light receiver30may be located at substantially the same position as the corresponding first slit90in the width and length directions in a plan view. The light receivers30each have an upper surface at a distance of 50 to 1,000 μm from the bottom surface of the first slit member20. This structure allows light scattered by the cells60and passing through the first slits90in the first slit member20to travel without reaching the light receivers30. This reliably prevents the light receivers30from receiving the scattered light. This structure can thus detect proliferated cells more accurately. The multiple light receivers30may be located on the upper surface of a base80(shown inFIG. 2) formed from a glass substrate or a plastic substrate.

The culture vessel40may include, for example, a Petri dish, a flask, and a microwell plate. The culture vessel40may have any shape or size, but may typically have one or more spaces suitable for proliferating the cells60. For example, a Petri dish may have a width or a diameter of several centimeters to several tens of centimeters and a height of several millimeters to several centimeters. A flask may have a width or a diameter of several centimeters to several tens of centimeters and a height of five to several tens of centimeters. A microwell plate may have a width or a diameter of several centimeters to several tens of centimeters and a height of 0.5 to several centimeters. The culture vessel40is formed from an optically transparent material, such as a plastic material or a glass material to be observable from outside. The microwell plate has wells each in the shape of, for example, a circle, a rectangle such as a square, or a polygon such as a pentagon or a hexagon. The circular well is suitable for isometric proliferation of cells, allowing effective proliferation of the cells60. The hexagonal well is suitable for the closest arrangement of wells, effectively reducing the size of the microwell plate. The culture vessel40accommodates the cells60and the culture medium70. More specifically, the culture vessel40may be a commercially available cell culture vessel, such as a cell culture plate, a cell culture flask, or a cell culture dish. These cell culture vessels typically include lids and are formed from a transparent resin. The culture vessel40may include multiple cylindrical containers for accommodating the culture medium70. The culture vessel40may be first attached to the cell detector100without the cells60and the culture medium70, and then receive the cells60and the culture medium70. In some embodiments, the culture vessel40accommodating the cells60and the culture medium70may be attached to the cell detector100. The culture vessel40can be removed from the cell detector100once the cells60have undergone sufficient proliferation. After the cells60and the culture medium70are collected, the culture vessel40may be washed, sterilized, and reattached to the cell detector100for another use.

The light receivers30may be located below the bottom surface of the first slit member20and directly below the culture vessel40. In this case, the cells60are cultured in the culture vessel40accommodating the culture medium70. The cells60may adhere to the upper surface of the first slit member20or may be suspended in the culture medium70. This structure can avoid adherence of the cells60and the culture medium70to the light receivers30. The light receivers30are thus reusable without being washed and sterilized.

The first slit member20and the light receivers30may be located directly below the culture vessel40. In this case, the cells60are cultured in the culture vessel40accommodating the culture medium70. The cells60may adhere to the bottom of the culture vessel40or may be suspended in the culture medium70. This structure can avoid adherence of the cells60and the culture medium70to the first slit member20and the light receivers30. The first slit member20and the light receivers30are thus reusable without being washed and sterilized for multiple culture vessels40.

The first slit member20and the light receivers30may be located directly above the bottom surface of the culture vessel40. For example, the light receivers30may be located between the bottom surface of the first slit member20and the bottom surface of the culture vessel40. In this case, the first slit member20and the light receivers30may be located in the culture medium70. The cells60may adhere to the upper surface of the first slit member20or may be suspended in the culture medium70. The first slit member20and the light receivers30may be disposable products to save the burden of washing and removing the cells60and the culture medium70and sterilizing the first slit member20and the light receivers30.

The culture medium70may be any commercially available cell culture medium and is selected as appropriate for the cells60to be used. The culture medium70may be, for example, a Dulbecco's modified Eagle's medium when mammalian cells are to be cultured. The culture medium70may further contain additional components used for culturing the cells60, such as bovine serum albumin, growth factors, amino acids, and antibiotics.

Cell culture typically involves medium replacement or subculturing every 2 to 4 days. Once the cells60have undergone sufficient proliferation in the culture vessel40, the cells60and the culture medium70are collected to replace the culture medium or subculture. The collected cells60and the culture medium70may be used in subsequent experiments.

In a modification of the present embodiment, the cell detector100may include a light emitter10, a culture vessel40accommodating a culture medium70containing cells60, a first slit member20including first slits90, and light receivers30that receive light emitted from the light emitter10and passes through the culture medium70and the first slits90in the stated order. The first slit member20may cause light emitted from the light emitter10and scattered by the cells60in the culture vessel40to avoid reaching the light receivers30.

Second Embodiment

FIG. 4is a schematic view of a cell detector101according to a second embodiment. The cell detector101according to the present embodiment includes a light emitter11, a first slit member21including first slits91and first light shields96, light receivers31that receive light emitted from the light emitter11and passing through the first slits91in the first slit member21, and a culture vessel41for culturing cells.

The first light shields96in the first slit member21blocks light emitted from the light emitter11and scattered by the cells61in the culture vessel41. The cell detector101further includes a second slit member22between the first slit member21and the light receivers31. The second slit member22includes second slits92and second light shields97.

FIG. 5is a block diagram of the cell detector101according to the second embodiment. In the present embodiment, the light emitter11, the first slit member21, the light receivers31, the culture vessel41, a determiner51, the cells61, the culture medium71, the first slits91, and the first light shields96are the same as those in the first embodiment unless otherwise specified and will not be described repeatedly.

The second slit member22blocks light passing through the first slits91in the first slit member21and scattered by the cells61and thus causes the scattered light to avoid reaching the light receivers31. The second slit member22may have the same shape as the first slit member21and may be located at substantially the same position as the first slit member21in the width and length directions. The first slits91in the first slit member21and the second slits92in the second slit member22may substantially overlap each other in a plan view. Light emitted from the light emitter11and passing through the first slits91without being transmitted though the cells61may substantially entirely pass through the second slits92. This structure increases the rate of decrease in the amount of light received by the light receivers31caused by the scattered light. This allows more accurate detection of the proliferation of the cells61.

The second slit member22may have its upper surface at a distance from the bottom surface of the first slit member21to more effectively block the scattered light. The second slit member22may have the upper surface at a distance of 1 to 100 μm from the bottom surface of the first slit member21. This structure allows the second slit member22to sufficiently block the scattered light passing through the first slits91in the first slit member21, preventing the scattered light passing through the first slits91in the first slit member21from passing through the second slits92in the second slit member22and reaching the light receivers31.

The second slits92each may have a shape similar to the first slit91, and may have the same or a different dimension as or from the first slit91. For example, when the distance between the bottom surface of the first slit member21and the upper surface of the second slit member22(distance D12) is shorter, the dimension of the second slit92may be the same as the dimension of the first slit91. When the distance D12is longer, the dimension of the second slit92may be larger than the dimension of the first slit91. When the distance D12is longer, light scattered by the cells61may diffuse over a larger area, and the culture medium71within the distance D12absorbs more light, thus possibly lowering the sensitivity of the light receiving elements. When, for example, the distance D12is shorter than or equal to the dimension of one cell61(about 10 to 50 μm), the second slit92may have the same dimension as the first slit91. When the distance D12exceeds the dimension of one cell61, the second slit92may have a larger dimension than the first slit91. In this case, the second slit92may have an opening area greater than one time and less than or equal to two times the opening area of the first slit91.

The second light shields97in the second slit member22may be formed from, for example, a light-shielding material including a black metal layer such as a chromium (Cr) layer or a black resin layer (black matrix) located in a portion of the lower surface (the surface facing the light receivers31) of a transparent substrate excluding the second slits92. Examples of the transparent substrate include a glass substrate and a plastic substrate. The light shields97may be formed from a light-shielding material located in a portion of the upper surface (the surface facing the light emitter11) of the second slit member22excluding the second slits92.

The first slit member21, the second slit member22, and the light receivers31may be located directly below the culture vessel41. In this case, the cells61are cultured in the culture vessel41accommodating the culture medium71. The cells61may adhere to the bottom of the culture vessel41or may be suspended in the culture medium71. This structure avoids adherence of the cells61and the culture medium71to the first slit member21, the second slit member22, and the light receivers31. The first slit member21, the second slit member22, and the light receivers31are thus reusable without being washed and sterilized for multiple culture vessels41.

The light receivers31receive light passing through the first slits91in the first slit member21and through the second slits92in the second slit member22without being transmitted through the cells61and light traveling straight after transmitted through the cells61. Each light receiver31may include, for example, a light receiving element such as a silicon photodiode.

The light receiver31may have dimensions in the width and length directions larger than those of the second slit92in the second slit member22. Light passing through the first slits91in the first slit member21is sufficiently blocked by the second slit member22. The light receivers31may include multiple light receiving elements. For example, the multiple light receiving elements are arranged to cover the bottom surface of the culture vessel41. As in the structure inFIG. 2, the light receivers31may be located on the upper surface of a base81formed from a glass substrate or a plastic substrate.

The light receivers31may be located between the bottom surface of the second slit member22and the bottom surface of the culture vessel41. In this case, the first slit member21, the second slit member22, and the light receivers31may be located in the culture medium71. The cells61may adhere to the upper surface of the first slit member21or may be suspended in the culture medium71. The first slit member21, the second slit member22, and the light receivers31may be disposable products to save the burden of washing and removing the cells61and the culture medium71and sterilizing the first slit member21, the second slit member22, and the light receivers31.

The light receivers31may be located below the bottom surface of the second slit member22and directly below the culture vessel41. In this case, the first slit member21and the second slit member22may be located in the culture medium71. The cells61may adhere to the upper surface of the first slit member21or may be suspended in the culture medium71. This structure avoids adherence of the cells61and the culture medium71to the light receivers31. The light receivers31are thus reusable without being washed and sterilized. The first slit member21and the second slit member22may be disposable products to save the burden of washing and removing the cells61and the culture medium71and sterilizing the first slit member21and the second slit member22.

The first slit member21is located under the cells61, the second slit member22is located directly below the first slit member21, and the light receivers31are located directly below the second slit member22. This structure allows detection of the scattering intensity of scattered light as a difference in the light detection intensity, allowing detection of the cells61.

Detection Method

Third Embodiment

FIG. 6is a flowchart of a cell detection method according to a third embodiment.

The cell detection method according to the present embodiment is implementable with the cell detector according to the embodiments of present invention. The method includes placing the culture medium and the cells in the culture vessel (placement A1), culturing the cells (culture A2), illuminating the culture medium containing the cells with light emitted from the light emitter (illumination A3), and obtaining an amount of light passing through the first slit member and received by the light receiver, or an amount of light passing through the first slit member and the second slit member and received by the light receiver (light amount obtainment A4).

Placement A1includes placing the culture medium and the cells in the culture vessel. The culture medium and the cells may be placed simultaneously. More specifically, the culture medium mixed with the cells may be placed in the culture vessel. After the culture medium is placed in the culture vessel, a small amount of culture medium containing cells may be placed further. The culture medium may be selected as appropriate for the type of the cells.

Culture A2includes culturing the cells. The conditions for culturing such as the temperature, duration, and atmosphere may be selected as appropriate for the cells and the culture medium.

Illumination A3includes illuminating the cells in the culture medium with light emitted from the light emitter. Illumination A3is performed, for example, after culturing the cells for a period predetermined for the type and the number of cells and the type and the amount of culture medium.

Light amount obtainment A4includes obtaining an amount of light received by the light receivers. As the cells proliferate, the amount of light transmitted through and scattered by the cells increases. The amount of light received by the light receivers is thus decreased.

In the present embodiment, the method may further include, after light amount obtainment A4, determining whether the cells have proliferated to a predetermined number or greater in response to an amount of the light received by the light receivers being smaller than or equal to a predetermined amount (determination A5). In determination A5, the amount of light received by the light receivers when the cells after sufficient proliferation are illuminated with light may be measured in advance as appropriate for the types of the cells and the culture medium, the number of the cells and the amount of the culture medium placed in the culture vessel, and the type of the culture vessel. In response to the cells being dense in the culture vessel and the proliferation rate being decreased in accordance with the types of the cells and the culture vessel or other factors, the cells may be determined to have proliferated to the predetermined number or greater. In determination A5, the determination may be repeated periodically, for example, every minute, every hour, or every day, before the amount of light received by the light receivers reduces to smaller than or equal to the predetermined amount.

As described in the above embodiments of the present invention, for example, the light emitter is located above the culture vessel accommodating the culture medium containing the cells, the light receivers are located below and face the light emitters with the culture vessel in between, and the first slit member including the first slits and the first light shields is located inside or outside the culture vessel. The structure may include multiple sets of the light emitter, the first slit member, and the light receivers. The light emitter may be located laterally to the culture vessel accommodating the culture medium containing the cells, the light receivers may be located laterally and face the light emitters with the culture vessel in between, and the first slit member including the first slits and the first light shields may be located inside or outside the culture vessel. This structure may include multiple sets of the light emitter, the first slit member, and the light receivers. The above structures allow more accurate estimation of the number of cells.

Although the embodiments of the present disclosure are described above specifically, the present disclosure is not limited to the above embodiments, but may be changed and modified variously without departing from the spirit and scope of the present disclosure. The components described in the above embodiments may be entirely or partially combined as appropriate unless any contradiction arises.

REFERENCE SIGNS LIST