Rod cells and cone cells in our eyes are visual photoreceptors in the retina that transform the visible light into nerve signals. Our perception of light is limited to what we call "visible light", i.e. wavelengths from 390 to 780 nm (violet to red). But some animals can see infrared or ultraviolet light as well.
I wonder if the limiting wavelengths are related to the size of our cone and rod cells, such as the size of an antenna is related to the wavelength of EM waves it can sense. If this is the case, would it be possible, with today's biotechnologies, to increase or decrease the size of these cone and rod cells to create (in vitro) a new retina which could see IR or UV light, or even further wavelengths?
The spectral sensitivity of individual photoreceptors is related to the photopigment they contain. Some vertebrates (notably Teleost fish) exhibit differences in these photopigments that are correlated with outer segment length; e.g. zebrafish retina contains four spectral cone types: LWS (long wavelength sensitive), MWS (middle wavelength sensitive), SWS (short wavelength sensitive), and UVS (ultraviolet sensitive), and these photopigments overlap with four morphological cone subtypes: long and short members of double cones (LWS and MWS respectively), long-single cones (SWS) and short-single cones (UVS) ((Branchek T, Bremiller R (1984) The development of photoreceptors in the zebrafish, Brachydanio rerio. I. Structure. J Comp Neurol 224: 107–115.)) However, this relationship between greater cone length and longer wavelength sensitivity is not ubiquitous across species.
Thank you Carl, so I understand this is more a chemical process than a physical one, related to the size of the photoreceptor.
That is correct Fabrice, but the physical components do have an influence on sensitivity to polarized light and directional sensitivity.
To my knowledge this relationship does not exist. But the size of cones is related (inverse relationship) to visual acuty, person with smaller cones has a high visual acuity, in other words is able to see smaller objects.
I just can add a bit to what Carl Bassi said. Grossly, spectral sensitivity of a photoreceptor is determined by the absorbance spectrum = structure of its visual pigment. Variations in the protein part (opsin) of the molecule plus a choice of one of two chromophores (vitamin A1 and 2) tune the spectral sensitivity to the entire range of visible wavelengths. However, there are optical effects somehow similar to the UHF antenna-like effects in photoreceptors. The effects are small, though, and cannot markedly shift spectral sensitivity.
As for extending human range of the visible spectrum, there are a few approaches. For instance, human do not normally see UV just because their lenses do not transmit below ca. 400 nm. Photoreceptors themselves, both rods and cones, are remarkably sensitive down to at least 280 nm. Thus, to see in the UV, undergo an eye surgery and replace your crystalline lens with an old-fashioned plastic lens without the UV block which is present in all modern artificial lenses.
Moving further to red also seems thinkable. One needs to replace natural A1-chromophore with A2. This would shift the spectral sensitivity by ca. 50 nm towards red/IR. An experimental protocol could be suggested.
Yet better use UV- or IR-sensitive cameras, and other physical gadgets that extend our sensitivity to gamma-rays and radio frequencies.
Yes, it may be possible by realising it with array of quantum antennas .
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