The invention presents a method to receive a positive indication in case of unwrapping, tearing or puncturing of any part of a package consisting, either entirely or in the form of a laminated layer, of electronic paper. Aside the indication being clear-cut, When used in connection of other security measures, aimed for authentication and preventing undetected tampering of the related devices and mechanisms, unnoticed trespassing past the sealing, which may cover the entire package, is extremely difficult.

Essential features of the invention include:

a 2 or 3-dimensional, dense pattern of thin (<100μm) conductive lines on electronic paper, covering to area to be protected against unauthorised ac- cess into the package. The area in question may comprise the entire outside surface of the package. The pattern is so formed that if a conductive line will be cut at any point of its length, or, if a short circuit will be present between adjacent lines at any point of the electronic paper it will be notified through measuring the difference in the flow of current fed into the circuit formed by the lines. The simplest form of this pattern is depicted in Figure 1. The novelty is the 2- or 3-dimensional pattern combined with a flexible material, since 1-dimensional solutions (a simple wire through e.g. handles of valuable products etc.) are currently used for surveillance, but they cannot handle surfaces.

The lines of the patterns need to be conductive, but the specific value of conductance is irrelevant since only definite loss of conductance or short circuit needs to be detected. This fact, and the dependence on dense line patterns, sets the invention apart from the solutions involving exact measurement of the specific conductance value of a surface (where some conductive material is embedded) , where minute variance of the measured conductance might be detectable in case of a worn out surface.

The 2 parallel lines in the pattern of figure 1 are continuous, terminating in a resistor shown at the far right bottom of the figure. This arrangement guarantees that if it will be cut at some point, as a result of, say, a puncture made by an injection needle, the closed electrical circuit formed by the lines and the resistor will be broken. Also, if the exemplary needle creates a short- circuit between two parallel lines, this also will be noticed since the resistance of the circuit will drop to near zero.

The gap through which an attack is possible is limited by the thickness and distance of the lines, and depends thus on the technology used. It is already easy to reach values below lOOμm, and in the near future substantial improvements are to be expected, so even an attack performed with the thinnest of injection needles would be impossible. The capability of detecting very small punctures can be further improved by special 3-dimensional patterns, e.g. by shifting the position of lines in consecutive layers like presented in Figure 4. In addition, by adding redundancy this arrangement also gives the possibility to estimate the condition of the package (the outermost lines are likely to suffer first in case of wear and tear) .

Several arrays of lines can form a matrix, either in one plane or in two, forming a 3-dimensional struc- ture, if indication about the whereabouts of the point of rupture on the surface of the package is required. In Figure 2 a single plane arrangement is presented, and in Figure 3 there is a matrix capable of indicating the compromised region of the surveyed package area, the tolerance being the amount of deployed amount of columns and rows of basic patterns. An even number of basic patterns can be combined so that the measuring currents arrive in opposing phases, thus reducing possible induced electrical noise from external sources. Any combinations of the basic arrangements discussed above are possible, with any number of planes.

In the figures only the patterns, without driving electronics, TPM modules etc. are depicted.