Abstract: Methods of detecting bioactive compounds include exposing compounds to one or more classes of chromatophores and measuring or sensing associated changes in one or more of the chromatophores. Representative methods permit identification and quantification of neurotransmitters, toxins, hormones, and chemical warfare agents with or without prior knowledge of the content of a sample. In some examples, chromatophores based on Betta fish are used. Cytosensor apparatus using such chromatophores include means for exposing chromatophores to a sample and optical detection systems for assessing changes in chromatophore optical properties. Compounds can be identified or quantified based on a red-green-blue or hue saturation-value representations of transmitted or reflected light or based on other characterizations of transmitted or reflected light.

Abstract: Apparatus is disclosed for modulating the R(18) or the R(24) lines of the (00.degree.1 - 10.degree.0) vibrational band of a C.sup.13 O.sub.2.sup.16 laser using Stark-tuned absorption resonances in N.sup.14 H.sub.3. A dc electric field is applied to a Stark cell containing N.sup.14 H.sub.3 gas to tune the asQ(6,6) absorbing transition in N.sup.14 H.sub.3 so as to overlap the R(18) laser line or the asQ(2,2) transition so as to overlap the R(24) line. Modulating frequencies approaching 300 MHz can be employed, and a 100% modulation depth is achievable with audio modulating frequencies. Unsaturated modulation has been obtained using a Stark cell of 10 cm length and containing N.sup.14 H.sub.3 gas at a pressure of 0.45 Torr for a laser power density of 12 watts per cm.sup.2.