FIELD OF THE INVENTION

The present invention relates generally to dosimeters and, more particularly, to automated dosimeters.

BACKGROUND OF THE INVENTION

Volatile- and semivolatile organic compounds (VOC and SVOC, respectively) are classes of compounds that have high vapor pressure at room temperature resulting from a low boiling point. While many naturally occurring VOCs are harmless (such as scents or pheromones), others are acutely toxic and/or have respiratory, allergic, or immune effects on organisms. These harmful VOCs and SVOCs include, for example, benzene, dichlorobenzene, ethanol, formaldehyde, terpenes, toluene, xylene, polybrominated flame-retardants, phthalates, pesticides, and polycyclic aromatic hydrocarbons. Still more dangerous VOCs and SVOCs may include agents used in chemical warfare.

Personal dosimeters are devices worn by individuals such that their exposure to harmful agents may be identified, quantified, or both. Dosimeters operate according to Fick's Law, where a sample amount, Q, adsorbed onto a sampling media may be expressed as a function of a compound specific diffusion coefficient, D, and a geometric constant of the dosimeter, K:
Q=D*K
Because the diffusion coefficient remains constant, improvements to a measured sampling rate requires manipulating the geometric constant, K. This geometric constant is a function of a cross-sectional area of a diffusion path, A, diffusion path length, L, an airborne concentration, C, and a sampling time, T:

K=(AL)*C⁢T.

Therefore, personal dosimeters conventionally include a tube, badge, or other similar style that is worn during the possible exposure. For accurate analysis, the exposure time, both date and time, must be specifically recorded. While this may be an inconvenience to individuals within a laboratory setting, it can be difficult to impossible to individuals working in the field.

Besides timekeeping, conventional, passive dosimeters present other difficulties. Those devices utilizing a power source require battery replacement or recharging. Manipulating small batteries and components is not feasible in the field, particularly in the field of battle, when a soldier may be carrying a large weight of gear.

In view of these conventional devices, there remains a need for a passive dosimeter that self-reports exposure times, is replaceable, and configured in a manner that facilitates quick and ease of use.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing problems and other shortcomings, drawbacks, and challenges of conventional, passive dosimeters. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. To the contrary, this invention includes all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention.

According to one embodiment of the present invention a self-timing, passive, chemical dosimeter includes a sampling media and electronics supported by a cassette. The sampling media is configured to absorb volatile organic compounds, semivolatile organic compounds, or both, while the electronics are configured to record a time of exposure. The dosimeter further includes an actuator having a closed position and an open position. In the closed position, the actuator resists exposure of the sampling media to volatile organic compounds, semivolatile organic compounds, or both, and in the open position, the actuator permits exposure of the sampling media to volatile organic compounds, semivolatile organic compounds, or both. The actuator is configured to operate the electronics for recording time of exposure.

Other embodiments of the present invention are directed to a method of measuring exposure to volatile organic compounds, semivolatile organic compounds, or both using a dosimeter. The method includes moving an actuator of the dosimeter from a closed position to an open position. Movement of the actuator to the open position exposes a sampling media, which is configured to absorb volatile organic compounds, semivolatile organic compounds, or both if present. Movement of the actuator to the closed position resists exposing the sample media. Movement of the actuator is also configured to activate electronics that are configured to record a date and a time of the movement.

Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

