Praise be to Allah.
There is nothing wrong with depicting tiny organisms (bacteria and viruses) and using these images on a poster in the laboratory and the like, because depicting animate beings, if the features – such as the eye, nose and mouth – are not clear – does not come under the heading of haraam images, because there is no competing with or trying to match the creation of Allah.
The features may be unclear if the image is so small that the details are not clear to the viewer, or if the features are erased altogether.
The Hanafi fuqaha’ have stated that it is not makrooh (disliked) to pray in the presence of small images in which the features are not clear.
It says in ad-Durr al-Mukhtaar: It is not makrooh [to pray] if the [image] is beneath his feet or in the place where he sits, because in that case it is not being respected or venerated, or if it is on his hand or body and is covered with his clothes.
Or if it is on his ring, if it is an unclear engraving. It says in al-Bahr: We may understand from this that it is makrooh if the features are clear, not what is covered with a bag or other cloth, and the author agreed with him.
Or if the image is small, so that the features of its limbs are not clear to one who is standing, when it is on the ground.
Ibn ‘Aabideen said in his commentary (1/648):
The phrase “if the features of its limbs are not clear…” is more precise than what al-Quhustani said, when he said, “so that it is not clear to the one who looks at it except by staring too much,” as was mentioned by al-Karmaani, or if it is not clear to him from a distance, as mentioned in al-Muheet. Then he said: But if it is in a cupboard, if the image is a size of a bird, it is makrooh, but if it is smaller than that, then it is not. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: With regard to the image of which the features are not clear, even though there are limbs and a head and a neck, but there are no eyes or nose, there is nothing wrong with it, because this is not competing with or trying to match the creation of Allah.
And he [may Allah have mercy on him] was asked about the ruling on making something like dolls out of clay, then immediately squashing the clay into a ball.
He replied: Everyone who makes something to compete with or try to match the creation of Allah is included in the hadith, which speaks of the Prophet (blessings and peace of Allah be upon him) cursing the image-makers, and he said: “The most severely punished of the people on the Day of Resurrection will be the image-makers.”
But as I said, if the image is not clear – i.e., it has no eyes, nose, mouth or fingers – then this is not a complete image, and does not come under the heading of competing with or trying to match the creation of Allah, may He be glorified and exalted.
End quote from Majmoo‘ Fataawa ash-Shaykh Ibn ‘Uthaymeen (2/278-279).
See also the answer to question no. 241334.
And Allah knows best.