Novel developments in antibody micro-array technology allow the development of very sensitive instrument that is
capable of detecting a wide variety of different biomarkers from a sample liquid. An international consortium led by the
UK is currently developing the Life Marker Chip as an analytical instrument for the ExoMars mission in 2018 based on
the use of immunoassay technique.
In this paper it will be discussed how micro/nano system hardware has been designed and the connected fabrication
technology has been developed, compatible with the requirements of a Mars mission instrument and allowing a seamless
integration in the instrument.
A microfluidic fused silica chip integrates all the relevant components for the analysis/assay procedure (except the
pumping, which is performed by a syringe-type bellows pump). The fluidic chip therefore contains an entries for intake
of the pretreated sample, chambers for the solution of preloaded reagents and the hybridization reaction, liquid front
sensors, inputs and output ports for the selector valve and a channel structure connecting these components. Moreover,
the design has three parallel fluidic pathways in order to allow for three different classes of assays. The whole fluidic
design is driven by the requirement that the dead volumes and the total liquid volume are as small as possible. It
appeared that a miniaturized and integrated selector valve has far better properties than a system with numerous
integrated and externally, often pneumatically actuated on-off valves. Next to this, the connected volume and mass of the
whole fluid management system is lower.
An optical array chip incorporates integrated waveguides, which allow for excitation of the fluorescent labels by the
evanescent field of the guided light wave. The system had to be designed in such a way that the light of a single fibercoupled
lightsource is distributed over all the spots (10 x 10) of the array. The LioniX proprietary waveguide technology
TriPleX is the only mature technology that allows this in the required (VIS) wavelength region. The losses of this
silicon-nitride based waveguide system are extremely low while allowing bends necessary to distribute the light over a
matrix of spots.