The Weeds family is comprised of a cost-effective, mass-produced, and biodegradable system of connecting elements (the substrate) which are printed with a thermochromic skin. Each of these elements will be capable of connecting to all others, as well as to a variety of materials that are generally present in the Manhattan sidewalk environment. And because they will be coated with a thermochromic, liquid crystal layer, they will be able to change color in response to subtle variations in temperature (we have been able to program these chemical sensors to a precision of +/- 1 degree Celsius and we can define the color that a particular temperature elicits).

A liquid crystal thermometer is a type of heat sensor that contains temperature-sensitive (thermochromic) liquid crystals. These thermometers use the phase changes that occur in crystaline lattices at different temperatures as increments and, as a result, can be tuned to respond to heat differentials relatively rapidly — quickly enough, in fact, to generate visual traces of convection (as well as conduction and radiation) as it occurs.

Bioplastic is a raw material, created by complexing starch with polyesters, that is both biodegradable and compostable. A combination of bio-active compounds and swelling agents ensures that the plastic's molecular structure will expand when exposed to a combination of heat and moisture, thereby enabling the bio-active agents to metabolize this plastic. Depending on material type and environmental conditions, decomposition of Bioplastic can be expected to occur in 10-45 days.

While preparing this proposal, we devoted substantial time and energy to an examination of the codes that define Manhattan sidewalks. A significant portion of this research concerned legal codes and ways in which such policy is enforced (we were searching for ways to benchmark more ambiguous aspects of the environment). What we found, as might be expected, was a stark distinction between concept and practice. In Manhattan, for example, property owners are responsible for cleaning a portion of the street, extending 18 inches out from the curb, that runs along their property, but there is little evidence of people shouldering this responsibility. Even when guidelines are clear they are rarely salient in the complex and dynamic sidewalk environment (the fine for noncompliance with the aforementioned code, according to the 2004 NYC Department of Sanitation Guidelines, is $100-$300 per violation, but tickets can be issued between 8-9 AM and 12-1 PM). In light of this issue, we have decided to take a laissez-faire approach to the maintenance of our Weeds. Once they have been disseminated, their ability to survive and propagate will depend upon dynamics that we will make to effort to control.

Four weeks after we have deployed the Weeds, we will revisit the five sites were they where seeded and dispose of any remaining residue — most of the material from which they will be made is biodegradable — but it is our hope and expectation that some of these Weeds will escape into the city.