A phone at the eyepiece

Count cells from a phone photo of a hemocytometer.

Hold a modern phone to the microscope eyepiece, photograph one full 1 mm square of the hemocytometer with its rulings crisp, and CellCount measures the grid in the photo (or you place the crossings by hand if the rulings cannot be found), counts the cells inside it and reads trypan blue viability. No adapter and no hardware: the phone you have is enough for a count you can check.

Updated

What the photo needs

  • One full 1 mm square, with all four corners, inside the frame. The rulings are what the scale is measured from, so the count needs the whole square, not most of it.
  • Rulings crisp. If the lines are soft the cells are softer, and a blurred cell is a missed cell or a wrong live-or-dead call. If the rulings cannot be found in a photo, you can place the grid’s crossings by hand.
  • Full resolution, no zoom. Frames under about 2,000 pixels on the short side are too small to count reliably, and digital zoom throws pixels away. A modern phone’s main camera clears this easily; a front camera or an old phone may not.
  • Even light. The background bright but not white, detail kept in the blue cells. Blown highlights erase dead cells and crushed shadows erase live ones.
  • JPEG, PNG, TIFF. HEIC and HEIF photos are converted to JPEG in the browser on Safari and iOS, the only browsers that can decode them; elsewhere, export the photo as JPEG first. Nothing is resized on the way in.
Two frames side by side. Left, choosing hardware: the counted square plus a margin on each side has to fit the photo's short side. Right, judging one image: once the square has been found on the image, the square itself only has to fit.
What “the whole square” means. A setup is chosen so the counted square fits the photo’s short side with a 5% margin on each side; one photo only needs the square itself inside the frame once the square has been found on it.

Which objective, which photo size

Held to the eyepiece, a phone has no adapter, so two things set how many pixels land on each millimetre of the chamber: the objective, and the size of the photo. A higher objective spreads the cells over more pixels, which suits small cells and dense samples, and the smaller squares of the ruling still fit where a whole 1 mm square no longer does.

Log-log plot of scale at the specimen against the photo's short side. Vertical lanes mark the photo sizes common phones take, from 12 megapixel defaults to 200 megapixel modes. Diagonal bands show a phone at the eyepiece at 10x, 20x and 40x; only the 10x point was measured, the rest is projected. Coloured regions mark in range, caution, under-resolved, and too magnified for a 1 mm square or for every square.
Where a phone at the eyepiece lands. Each band is one objective; only the 10× point was measured, the rest is projected from it, since common main cameras share about the same field of view. At 10× a 12 MP photo sits in the caution band and a 24 MP photo in range; at 20× every common photo size is in range for the smaller squares, most of them above the highest scale validated so far.

How to do it

A gloved hand holding a phone whose screen shows the hemocytometer grid and cells seen through the microscope eyepiece, with the shutter button below the round fieldA phone at the eyepiece of an inverted microscope, in a simple clamp, showing the chamber grid live on its screen while a gloved hand steadies it
The phone’s main camera against the eyepiece, the round field filling the screen and the rulings sharp before the shutter is pressed. A simple clamp, as on the right, keeps the phone steady for a series of photos; a hand on the microscope does the same job.
  1. 1

    Set the microscope first

    Use the 10x objective, bring the rulings into sharp focus and set the light so the background is bright but not white and the blue cells keep their colour. What you see in the eyepiece is what the phone gets.

  2. 2

    Hold the phone to the eyepiece

    Put the phone’s main camera lens flat against the eyepiece and centre it until the round field fills the screen. Rest your hands on the microscope. Tap the grid on the screen so the phone focuses and exposes on the rulings.

  3. 3

    Frame one full square

    Move the stage until one full 1 mm square, with all four corners, sits inside the field. Do not zoom: digital zoom throws away the pixels the count needs. Take the photo at the camera’s full resolution.

  4. 4

    Upload the photo

    Open CellCount on the phone itself, or send the photo to the laptop, and drop it on the counting page. CellCount measures the rulings in the photo (if it cannot find them, you place the crossings by hand), counts inside the square and applies the protocol’s dilution and sensitivity. HEIC photos are converted in the browser on Safari and iOS; elsewhere, export the photo as JPEG first.

  5. 5

    Check the marks and accept

    Every detected cell is drawn on your photo. Add, delete or flip the ones you disagree with, then accept the count. The concentration, the viability and the size histogram come with it, and so does the record of who accepted it and when.

What a phone count is good for

A check on a number you doubt, a second reading of a chamber somebody else counted, a count at a bench with no camera, a teaching lab, a field site. For cells of about ten micrometres and larger, which covers most mammalian cell lines and primary cells, a phone photo that meets the list above counts well. Smaller cells such as yeast want the resolution of a camera on the microscope port, and so does the daily bench count: the camera frames the same square at the same scale every time, counts live into the browser and never needs a steady hand.

The same protocol runs on a phone photo, a camera frame and a counter’s exported image, so a phone count from Tuesday and a camera count from Wednesday were made the same way and can be compared. The recommended setup is described on the About page.

What comes back

A gloved finger pointing at a phone at the microscope that shows a grid of counted hemocytometer photos, each with its viability and cell total
The counted photos of a session on the same phone, each with its viability and cell total.

Every detected cell marked on your photo, live and dead in their own colours; the count, the concentration in cells per mL from the measured grid and your dilution, the viability, and a cell-size histogram with the gate you set. The count is accepted by a named person, dated, sealed with a hash, and leaves as a results document or an export bundle with the image, its overlay and the results as CSV.

A phone photo counts on the Free plan like any other image, with no card needed. What the Free plan includes.

Book a demo on your samplesStart counting freeThe manual methodImage requirements