That’s a First! Scientists Build Artificial Eye That Can See Color

From red to blue, this chip deciphers color like your retina—and it never needs charging.

A recent study published in Scientific Reports by researchers at Tokyo University of Science represents a major leap toward solving one of neuromorphic engineering’s biggest puzzles: replicating the human eye’s ability to perceive color.¹

The team, led by Dr. Takashi Ikuno, has developed a self-powered optoelectronic artificial synapse that doesn’t just detect color—it mimics how our brains interpret it. This breakthrough brings intelligent, low-power machine vision closer to reality.

A color-sensing artificial synapse

Using dye-sensitized solar cells (DSCs), the researchers built a synaptic device that can recognize different wavelengths of light and respond with precision. Unlike previous artificial synapses, which focused on monochromatic detection, this one operates across the visible spectrum—something no other system has achieved.

At the heart of the system are two dye-sensitized solar cells (DSCs)—one tuned to short wavelengths (blue light) using a dye called D131, and another tuned to longer wavelengths (red light) with SQ2 dye. These DSCs convert light into electrical signals, but with a twist: depending on the wavelength, the output voltage shifts polarity. That means the device not only detects if light is present but also what color it is, using electrical cues.

How it works: Multidimensional light interpretation

What sets this system apart isn’t just its sensitivity, but how it processes information. Rather than relying solely on light intensity, it also reads polarity shifts and timing patterns—adding extra dimensions to the signal, similar to how biological neurons encode complex inputs.

The signal itself isn’t just a simple voltage blip. It encodes multiple layers of information:

Polarity: Positive for blue, negative for red
Temporal dynamics: How the signal changes over time
Amplitude variation: Reflecting intensity and stimulus frequency

This rich data stream allows the device to interpret complex patterns in much the same way human neurons do—through a process called synaptic plasticity, which enables learning and adaptation.

And it’s self-powered. Like a solar panel with a built-in neural processor, the synapse collects light, analyzes its properties and transmits data—all without an external power source.

What it can do: Brain-like behavior in a chip

This prototype isn’t just a color sensor—it’s a learning system. Through a process similar to how the brain processes repeated stimuli (known as paired-pulse facilitation), the synapse adapts based on previous inputs.

Here’s what the system achieved:

Color discrimination within 10 nanometers of precision with an accuracy of 82%
Logic functions like AND, OR and XOR
Pattern recognition, including classification of up to six-bit sequences
Motion recognition in color-coded video streams
An exceptional PPF index (a measure of synaptic memory) ranging from –3776 to 8075

From prototype to practical use

While the study is a major breakthrough, several technical hurdles remain as with any other breakthrough. The current system uses a liquid electrolyte, which limits long-term stability. Future iterations will likely transition to solid-state designs for durability and scalability. There’s also a need to fine-tune voltage outputs for clearer digital signal reading.

But this study offers a clear proof-of-concept: biological complexity can be emulated, and even exceeded by smart engineering.

In today’s world of smart machines, cameras and AI, energy consumption is a critical bottleneck—especially for systems that need to operate at the edge. Traditional machine vision systems are power-hungry, requiring multiple sensors and processors just to make sense of what they “see.”

This artificial synapse side steps that entirely. Inspired by biology, it offers a low-power, high-functioning model for next-gen vision systems—not just detecting shapes or movement, but understanding color, context and sequence in a compact, self-sufficient package.

As the researchers note, this isn’t just a sensor. It’s a model of cognition, opening the door to new possibilities in robotics, healthcare, wearable diagnostics and more.

Editor’s Note: This content is intended exclusively for healthcare professionals. It is not intended for the general public. Products or therapies discussed may not be registered or approved in all jurisdictions, including Singapore.

Reference

Komatsu H, Hosoda N, Ikuno T. Polarity-tunable dye-sensitized optoelectronic artificial synapses for physical reservoir computing-based machine vision. Sci Rep. 2025;15(1):16488.