Lab-on-a-Chip Instrumentation and Method for Detecting Trace Organic and Bioorganic Molecules in Planetary Exploration: The Enceladus Organic Analyzer (EOA)

Abstract:

Lab-on-a-chip instrumentation is providing an ever more powerful in situ approach for detecting organic molecules relevant for chemical/biochemical evolution in our solar system obviating the cost, risk and long mission duration associated with sample return. Microfabricated analysis systems are particularly feasible when directly sampling from comet comae, or ejecta from icy moons, such as targeting organic molecules in plumes from Enceladus. Furthermore, the superb ppm to ppb sensitivity of chip analyzers, like the Enceladus Organic Analyzer (EOA), coupled with the ability to examine organics with a wide variety of functional groups enhance the probability of detecting organic molecules and determining whether they have a biological origin.

The EOA is based on 20 years of research and development of microfabricated capillary electrophoresis (CE) analyzers at Berkeley that provide ppb sensitivity for a wide variety of organic molecules including amino acids, carboxylic acids, amines, aldehydes, ketones and polycyclic aromatic hydrocarbons [1]. Organic molecules are labeled with a fluorescent reagent according to their functional group in a programmable microfluidic processor [2,3] and then separated in a CE system followed by laser-induced fluorescence detection to determine molecular size and concentration.

The EOA will be flown through Enceladus plumes and uses a specially designed impact plate/door to capture ice-particles. After closing the door, the material in the capture chamber is dissolved, labeled and analyzed by the microfabricated CE system. Only a few thousand 2 µm diameter particles containing ppm organic concentrations will provide an EOA detectable signal. If amino acids are detected, their chirality is determined because chirality is the best indicator of a biologically produced molecule. We have developed a flight design of this instrument for planetary exploration that is compact (16x16x12 cm), has low mass (3 kg), and requires very low power.

[1] Skelley et al. (2005) PNAS USA, 102, 1041‐1046. [2] Kim et al. (2013) Anal. Chem., 85, 7682−7688. [3] Mora et al. (2012) Electrophoresis, 33, 2624-2638. [4] Stockton et al. (2014) Second International Workshop on Instrumentation for Planetary Missions, NASA Greenbelt MD, Nov. 4-7, 2014.