Roomba indoor air quality mapping

The RISD Environmental Justice Research Cluster in Providence uses a Roomba as a medium in order to reveal the condition of our surroundings. Roomba--the room cleaning vacuum--is programmed to travel all around a room once it is left to roam. Therefore, it is an ideal tool to assess the quality of air through out a room. We have attached a sensor and light system to these second hand Roombas. When our Roomba senses a change in air quality, currently an increase in the amount of volatile organic chemicals (VOC) in the air (we use alcohol as our test VOC) it emits a different color of light. If you take a long exposure image of our Roomba as it travels through a room, you can see the path its traveled by the light it emits. In areas where there are more VOCs the light on Roomba changes from green to blue. Looking at this image you can easily spot an area of indoor air-pollution. In the future we will be adding a sensor for formaldehyde to this Roomba. Formaldehyde is a very common indoor and harmful indoor air-pollutant.

Currently, we use MQ 135, an air quality sensor to express the condition of air. In the future, we can also use the wireless system or hack a roomba to control its movement as the quality of air.

Formaldehyde:

RISD blog:
http://dm.risd.edu/courseblogs/ejrc/?p=168

Hydrogen Sulfide:

Toxic effects (from http://www.osha.gov/dts/sltc/methods/validated/1008/1008.html):

1.1.2 Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy.)4

Symptoms observed from exposure between 5 and 2000 ppm are as follows:

1000 – 2000 ppm: Breathing stops due to paralysis of the respiratory system.

500 – 1000 ppm: Breathing rates speed up followed by temporary suspension of breathing at higher concentrations.

50 – 500 ppm: Respiratory tract and eye irritation. Prolonged exposures to concentrations between 50 and 600 ppm can cause pulmonary edema (swelling and accumulation of fluid in the lungs). Olfactory fatigue occurs at concentrations between 150 and 200 ppm.

5 - 50 ppm: Irritation of the eyes.

Long term effects from repeated hydrogen sulfide exposure have not been established but symptoms may include dizziness, headaches and fatigue. Hydrogen sulfide is not regarded as a cumulative toxin as it is quickly oxidized to sulfate and then excreted by the kidneys.

Sensors under investigation:
http://www.figarosensor.com/products/825pdf.pdf

http://www.apollo-sensors.com/s04/apollo-sensors/cpxx/20090703/7281027.html

Alternative Monitoring methods:

Silver:
http://www.osha.gov/dts/sltc/methods/validated/1008/1008.pdf
http://www.osha.gov/dts/sltc/methods/validated/1008/1008.html

Goals

The Roomba moves much too fast to produce good readings -- the sensors take 15-30 seconds to detect anything -- so the group is working on a few ways to slow down the robot. One is to mechanically gear down the wheels with a kind of "scooter":