| abstract |
An apparatus and method for determining the concentration of alcohol present in a gaseous mixture wherein an electronic device employing a fuel cell determines the concentration of alcohol present in the gaseous mixture is disclosed. In particular, the device may be used to determine a person's sobriety by determining the alcohol concentration in a breath sample. To determine the alcohol concentration, the device must be able to accurately determine the volume of breath in the breath sample. The device controls the volume of the breath sample by measuring the pressure of the breath flow through the device and, in response to the pressure, electronically controlling a valve diverting a portion of the breath flow into the fuel cell. One application of the invention is a sobriety interlock for a machine where the machine remains disabled unless the operator is first determined to have an alcohol concentration below a predetermined level. |