title: Biosensor microprobes with integrated microfluidic channels for bi-directional neurochemical interaction.
abstract: This paper reports on silicon-based microprobes, 8 mm long and 250 µm × 250 µm cross-section, comprising four recessed biosensor microelectrodes (50 µm × 150 µm) per probe shank coated with an enzymatic layer for the selective detection of choline at multiple sites in brain tissue. Integrated in the same probe shank are up to two microfluidic channels for controlled local liquid delivery at a defined distance from the biosensor microelectrodes. State-of-the-art silicon micromachining processing was applied for reproducible fabrication of these experiment-tailored multi-functional probe arrays. Reliable electric and fluidic interconnections to the microprobes are guaranteed by a custom-made holder. The reversible packaging method implemented in this holder significantly reduces cost and assembly time and simplifies storage of the biosensor probes between consecutive experiments. The functionalization of the electrodes is carried out using electrochemically aided adsorption. This spatially controlled deposition technique enables a parallel deposition of membranes and is especially useful when working with microelectrode arrays. The achieved biosensors show adequate characteristics to detect choline in physiologically relevant concentrations at sufficient temporal and spatial resolution for brain research. Sensitivity to choline better than 10 pA µm(-1), detection limit below 1 µM and response time of 2 s were obtained. The proposed combination of biosensors and microfluidic injectors on the same microprobe allows simultaneous chemical stimulation and recording as demonstrated in an agarose gel-based brain phantom.
authors.affiliation: Institute of Microengineering, École Polytechnique Fédérale de Lausanne, Neuchâtel, Switzerland. olivier.frey@bsse.ethz.ch
authors.forename: O
authors.initials: O
authors.lastname: Frey
authors.forename: P D
authors.initials: PD
authors.lastname: van der Wal
authors.forename: S
authors.initials: S
authors.lastname: Spieth
authors.forename: O
authors.initials: O
authors.lastname: Brett
authors.forename: K
authors.initials: K
authors.lastname: Seidl
authors.forename: O
authors.initials: O
authors.lastname: Paul
authors.forename: P
authors.initials: P
authors.lastname: Ruther
authors.forename: R
authors.initials: R
authors.lastname: Zengerle
authors.forename: N F
authors.initials: NF
authors.lastname: de Rooij
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D009420:Nervous System / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry
chemical_list: D017655:Silicon Compounds