Highlights
- Infrared light helps organize water inside the body. Scientists discovered that gentle infrared (IR) energy can make water molecules arrange into more structured, energized layers — known as Exclusion Zone (EZ) water.
- Infrared = gentle, not heat. The study confirmed that these effects come from the light itself, not from temperature, showing how subtle IR exposure can enhance order in water without heating it.
Interfacial water, also known as the exclusion zone (EZ), spontaneously forms at hydrophilic surfaces, creating distinct zones characterized by charge separation. Understanding the factors that influence the formation and expansion of these zones is fundamental to various fields, from biology to materials engineering. The study conducted by Wang and Pollack (2021) aimed to investigate the effect of infrared (IR) radiation on the dynamics of interfacial water on hydrophilic surfaces, specifically on Nafion membranes.
Intervention Used in the Study
To induce and observe the formation of interfacial water zones, the researchers used Nafion membranes, a highly hydrophilic material. The membrane was carefully immersed vertically in a chamber containing 1 mL of phosphate-buffered water (1 mM), to which microspheres and a pH-sensitive dye were added.
The chamber was constructed from a plastic block with a central cavity, resting on a 1 mm thick glass slide. The interfacial zones were observed over a period of 10 minutes using an inverted microscope (Axiovert 100TV, Zeiss). Images captured by a color camera (EO3112C) were processed using ImageJ software, enabling precise measurement of the exclusion zones (EZ) and proton zones (PZ).
For infrared irradiation, two types of LEDs were used:
- A mid-infrared (MIR) LED with a wavelength of 3.0 μm.
- Three near-infrared (NIR) LEDs with wavelengths of 810, 840, and 870 nm.
The light was focused through a 100 μm pinhole, with the LED positioned approximately 2 mm above the water level, directing radiation directly onto the exclusion zone. The LED currents varied between 25 and 250 mA, with output powers ranging from 5 to 50 μW for MIR. The sample was irradiated for 5 minutes, after which the zones were again observed and measured.
Additionally, an infrared camera (SC-6000, FLIR Systems) monitored thermal variations, ensuring that the observed effects were not caused by heating, but rather by the specific action of IR radiation.
Results Presented by the Study
The results showed that infrared radiation significantly promoted the expansion of interfacial zones:
- After 5 minutes of irradiation with MIR light (3.0 μm), the exclusion zone (EZ) expanded by 1.41 times.
- The proton zone (PZ), characterized by the accumulation of hydronium ions, also expanded significantly, with an estimated amount of approximately 1.39 × 10¹⁶ molecules.
Additionally, it was observed that:
- Infrared radiation not only promotes the formation of the EZ but also induces the release of protons from this zone into the bulk water.
- Irradiation with NIR light (810–870 nm) also caused expansion of the EZ and PZ, although it required much higher intensities.
- The interfacial zones formed around Nafion stabilized after 5 minutes, with average sizes of 575 μm (EZ) and 902 μm (PZ).
- The special structure of interfacial water favors charge separation, generating natural electric gradients.
It is important to note that thermal effects were minimal, indicating that the expansion of the zones resulted from photochemical and not thermal interaction between infrared radiation and water.
Authors’ Interpretation
The authors interpret that incident infrared radiation not only stimulates the accumulation of interfacial water at hydrophilic surfaces but also acts as a driving force for charge separation, forming a proton-rich zone (PZ) and a negatively charged exclusion zone (EZ).
The significant expansion of these zones under infrared irradiation suggests that IR light could be an important natural agent for generating charge gradients in water, with potential applications in converting this energy into chemical, mechanical, or electrical forms.
The authors also highlight the potential of harnessing the abundant and free infrared radiation from sunlight, representing a promising and challenging area of research for the development of new biophysical and energy technologies.
Reference: Wang A, Pollack GH. Effect of infrared radiation on interfacial water at hydrophilic surfaces. Colloid and Interface Science Communications. 2021; 42:100397. doi: 10.1016/j.colcom.2021.100397
Figure 1 – Formation of Exclusion Zone (EZ) Water at a Hydrophilic Surface. Schematic representation of how structured water (EZ water) forms adjacent to a hydrophilic surface. Water molecules near the surface become highly ordered, creating a negatively charged zone (EZ) that excludes solutes and particles. The region beyond remains disorganized, forming bulk water. This charge separation establishes an electrical gradient, which can expand under infrared (IR) light exposure.