Executive Summary: Diametryx Inc., a Boston, MA (USA)-based startup company, has experimentally demonstrated the first real-world samples of its core technology, a stimulus-responsive, color-changing particle-in-a-particle, for use in overt and/or covert authentication applications.

Problem to be Solved:

We aimed to develop the next generation of stimulus-responsive, color changing security materials that simultaneously satisfy several key criteria:

(1) Rapid, simple stimulation and response

(2) Unambiguous readout by the general public

(3) Ability to switch between any pair of colors, tunable on a per-customer basis

(4) New actuation mechanisms, including mechanical agitation (shaking) and gravity

(5) Unique compositions providing exceptional resistance to counterfeiting or simulation

Technical Description: The composition comprises a bi-chromic Janus particle encapsulated in a hollow shell (see Figure). The beauty of this “particle-in-a-particle” geometry is that while the outer particle is what is exposed to the external environment (and is immobilized in the carrier vehicle/ink), the inner particle is free to move in response to stimulation. In this early example, the core particle is approximately 4 microns in diameter. The Janus particle comprises an off-white portion(approximately a hemisphere) and a purple portion (also approximately a hemisphere). The core particle is designed to respond to a moving magnetic field. The outer edge of the spherical shell is approximately 8 microns in diameter. We can independently control the diameter of the inner particle, the thickness of the shell, and the void space (“internal real estate”) between them.

Function: As shown in the two videos provided, these particles respond to motion of a tiny magnet, both under the microscope and in bulk. In bulk, movement of the magnet leads to a clear change in color.

Presentation: This presentation will cover (a) performance of the particles in various vehicles and inks, (b) robustness to various printing methods, (c) compositions that respond to gravity, (d) examples of particles-in particles with different color pairs, and (e) the current status of scale-up