Using Nanotechnology to Develop Wearable, Rugged Cables with Unmatched EMI/RFI Protection

19 Sep 03

In February 2003, the US Army concluded developmental testing of Land Warrior-Initial Capability (LW-IC). The Army Rangers that tested LW-IC at Hunter Airfield, GA found that it failed to meet reliability requirements. Specifically, LW-IC exceeded the allotment of one mission failure per 158 hours of operation. As a result, in July 2003, the US Army cancelled LW-IC.

What caused LW-IC's failure? Short-lived batteries and short-ranged radios contributed, but the underlying cause of many communications failures and software glitches was electrical interference due to an MBITR radio introduced late in the project. The LW-IC's cables, connectors, or overmolds were not designed to withstand the resulting electromagnetic and radio frequency interference (EMI/RFI).

Shields protect cables from electrical interference. Typically, a shield is a metal covering that surrounds the inner conductor of a cable. The shield must be grounded so that interference that strikes the shield is safely conducted away to ground before it can reach the sensitive inner conductor.

Today, foil shields are the most effective means of protecting the inner conductor from high-frequency EMI/RFI.  Unfortunately, foil shields kink and tear when bent, so they are not well suited for body-worn applications such as the Land Warrior and Objective Force Warrior.

Minnesota Defense has teamed up with the University of Minnesota to develop a flexible, durable shield with EMI/RFI protection that rivals foil.  The trick is leveraging the unique properties of carbon nanotubes and dispersing them in a thermoplastic elastomer (TPE).  The end product will maintain its shielding effectiveness after thousands of flexes.

Figure 1: Based on research at the University of Minnesota, Minnesota Defense is developing a conductive polymer shield that incorporates carbon nanotubes.		Figure 2: The shield will enable flexible, durable cables with unmatched EMI/RFI protection.