title: Ex-vivo detection of neural events using THz BioMEMS.
abstract: BACKGROUND
  Electromagnetic frequencies up to a few terahertz (THz) can yield real-time and noninvasive measurements on biological matter. Unfortunately, strong absorption in aqueous solutions and low spatial resolution return difficult free-space investigations. A new approach based on integrated THz circuits was used. The authors designed and fabricated a BioMEMS (Biological MicroElectro-Mechanical System) compatible with microfluidic circulation and electromagnetic propagation. It is dedicated to the ex vivo detection of nitric oxide synthase (NOS) activity, which is involved in neurodegenerative phenomena.
  
  
  METHODS
  The biological model was a leech's central nervous system. After its injury, the production of NO was observed and measured in the far-THz spectral domain. The nerve cord was put inside a BioMEMS realized in polydimethylsiloxane (PDMS) sealed on a glass wafer. Glass is a good material for supporting high-frequency integrated waveguides such as coplanar waveguides (CPWs). Measurements were performed with vectorial network analyser (VNA).
  
  
  RESULTS
  The transmission parameter in the frequency range of 0.14-0.22 THz was measured through CPWs located just below the microchannel containing the injured leech nerve cord. The lesion caused a decreased transmission coefficient due to the NOS activity. L-NAME was injected inside the microchannel and it was verified that it inhibits this activity.
  
  
  CONCLUSIONS
  It was demonstrated that THz spectroscopy can detect a biochemical event, such as NOS activity around an injured leech's nerve cord, in real time. Future studies will be dedicated to quantitative measurements of the reaction products using the sophisticated management of several drugs allowed with microfluidic microsystems.
authors.affiliation: Institute of Electronic, Microelectronic, and Nanotechnology, BioMEMS Group, UMR-CNRS 8520, University of Lille, Lille, France.
authors.forename: Abdennour
authors.initials: A
authors.lastname: Abbas
authors.forename: Thomas
authors.initials: T
authors.lastname: Dargent
authors.forename: Dominique
authors.initials: D
authors.lastname: Croix
authors.forename: Michel
authors.initials: M
authors.lastname: Salzet
authors.forename: Bertrand
authors.initials: B
authors.lastname: Bocquet
mesh_terms: D000818:Animals; D002490:Central Nervous System / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047709:Hirudo medicinalis / Q000033:anatomy & histology / Q000502:physiology; D008280:Magnetics; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation / Q000379:methods; D044085:Microfluidics / Q000379:methods; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D055068:Terahertz Spectroscopy / Q000295:instrumentation / Q000379:methods
chemical_list: D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester