Researchers at the University of Hong Kong (HKU) have developed a groundbreaking technology known as Morphable Concavity Array (MoCA). This pixelated, soft, color-changing system has various applications in a wide range of industries, including healthcare, electronics, and fashion. Led by Dr. Yi Pan from the Department of Mechanical Engineering at HKU, the study was published in Advanced Science. This article explores the unique features and potential applications of MoCA.
MoCA, created by HKU researchers, consists of a thin rubber-like structure with two layers. The top layer is a photonic crystal elastomer actuator (PC-EA) film, while the bottom layer is a hole array. The PC-EA film comprises an elastomer layer on top and a hydrogel layer below. When ethanol is added to the hydrogel layer, it swells and pulls the elastomer layer downward, creating a concave shape called a morphable concavity (MoC). The formation of MoC blocks red light and changes the visible color of the pixel from red to blue. MoCA was inspired by the dual-color micro-concavities found on butterfly wings, which produce vibrant, iridescent colors.
MoCA stands out from other pixelated color-changing systems due to its ability to change local morphology. By transitioning between flat and concave states, MoCA can alter its color. Unlike conventional electrochromic methods, MoCA utilizes a multi-channel microfluidic system to introduce and remove solvents, enabling individual manipulation of each pixel’s color. This breakthrough allows for creative applications, such as concealing patterns or QR codes in clothing that are only visible under specific conditions.
MoCA has various potential applications in multiple industries. In the healthcare sector, it can be utilized in medical bandages that change color when an infection is present, providing a visual indicator to healthcare professionals. In the electronics industry, MoCA can be employed in foldable screens for smartphones and tablets, as well as wearable technology embedded within fabric. The ability to change focus individually also opens up possibilities for optical devices that mimic and surpass the capabilities of compound eyes found in insects.
MoCA’s unique color-changing properties make it a potential tool for counterfeiting prevention. By incorporating MoCA into products such as clothing, manufacturers can hide patterns or QR codes that can only be visible under specific conditions. This can help ensure the authenticity of products and protect against counterfeit goods.
While MoCA already offers impressive capabilities, the HKU research team has long-term goals of expanding its applications. By harnessing the principles of soft matter and microfluidics, they aim to construct optical devices that mimic and surpass the compound eyes of insects. Compound eyes provide advantages like a wider field of vision and the ability to focus on multiple objects simultaneously. MoCA’s ability to deform individual units can be used to create multiple lenses that can change focus individually, similar to the crystalline lens in the human eye. This integration would combine the advantages of both compound eyes and crystalline lenses, resulting in optical devices that imitate and transcend nature.
MoCA represents a significant advancement in pixelated, soft, color-changing systems. Its unique structure and ability to change local morphology make it an attractive technology for various industries. From medical applications to electronic screens and counterfeit prevention, MoCA has the potential to revolutionize multiple fields. Furthermore, the long-term goals of the HKU research team aim to push the boundaries of optical devices, creating systems that surpass the capabilities of natural vision. With continued research and innovation, MoCA opens up exciting possibilities for future advancements in color-changing technology.