Abstract: A new tip for a conventional lancer that provides for improved blood flow from a lancet puncture site not located on a patient's finger. The new lancer tip includes a plurality of crenellations that exert rotational force on the skin surrounding the lancet puncture site when the lancer is rotated to enhance blood flow from the lancet puncture site.

Abstract: Methods and apparatus for detecting biological activity within a sample are disclosed. The present invention provides a combination of a first and a second infrared light source arranged on the side of a sample vial, and a first and a second narrow-band infrared detector similarly arranged on the side of the vial approximately opposite the sources. The disclosed arrangement cancels the sources of error while measuring the carbon dioxide content of the headspace gas above the sample. In operation, the present invention sequentially measures the photocurrents generated at each detector with no source turned on, with the first source turned on, and with the second source turned on and the first source turned off. The CO.sub.2 absorption coefficient of the vial headspace gas is then calculated based on the photocurrents measured. This present invention allows compensation for source aging, detector aging, and vial wall thickness changes.