Development of new devices for toxin detection Carmen Moldovan, Rodica Iosub, Bogdan Firtat, Daniel Necula, *Eric Moore, *Gheorghe Marin IMT –Bucharest *Tyndall National Institute, Cork

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Development of new devices for toxin detection
Carmen Moldovan, Rodica Iosub, Bogdan
Firtat, Daniel Necula, Eric Moore, Gheorghe
MarinIMT BucharestTyndall National
Institute, Cork

Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Development of a toxin screening multi-parameter
on-line biochip system.  
ToxiChip Proposal No. 27900
Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
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Toxichip Objective

• Alternative in-vitro testing methods for the
  monitoring of toxichemicals
• A eukaryote cell based biochip that examines the
  effects of toxichemicals on cell impedance,
  morphology, distribution and pH
• A panel of genetically engineered bacterial
  strains that optically report on the presence of
  toxichemicals that normally affect eukaryotic
  cells
• A prokaryote based biochip that uses optical
  analysis to measure the signal (fluorescence,
  bioluminescence) emitted by the bacteria in the
  presence of different toxichemicals
• Develop a microfluidic system with temperature
  control and pH sensor

Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
4
Eukaryote cell-based biochip

• Comprise of finger electrodes composed of indium
  tin oxide (ITO)
• ITO will be used as an impedance sensor that
  allows real time non-invasive in-vitro analysis
• Biochip will function in a plug-in-play mode
  that will facilitate its insertion into the
  microfluidic platform

Bucharest, 6th of December
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Further Objectives

• specialised interfaces that links the biochip to
  a PC, that record data and provides on-line
  continuous information on microfluidics,
  electro-chemical signals, temperature and pH
• Develop a management software for project
  experiments, such as data acquisition, parameters
  control and data mining  
• Performance evaluation of the biochips will be
  done for the various integrated sensing
  capabilities - optical and electrochemical
  detection
• Characterise/Validate the biochips by using a
  combination of cellular bioassays and evaluating
  the biological effects of high doses and low
  doses, the impacts on DNA and endocrine
  perturbations on the bioassays.

Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
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Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
7
National Institute for Research and Development
in Microtechnologies (Romania)

• Microsystems research
• Simulation, design, technology, biosensors,
  electrodes for biological sensors, microprobes
  for recording of electrical activity of cells
• Technological development
• -Micromachining techniques for silicon, glass
  and ceramics,
• -Immobilization technique of enzymes on
  electrodes
• -Spin deposition of thin film sensitive polymers

Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
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Schematic of Toxichip Operating System
Electrode
Surface Chemistry
Cells


PC
EIS
Biochip

Platform Interface
Inverted Phase-contrast/Fluorescent Microscope
coupled with CCD camera
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications

of micro and
nanotechnologies
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Development of temperature sensor integrated
with the microfluidic platform

• Simulation and design of the temperature sensor
  together with the microfluidic part where the
  sensor is integrated.
• Study of the compatibility of the sensor with
  the chemical aggressive working environment.
• Biocompatibility of the microsensor materials
  with the biological media.
• Experiments, manufacturing design and testing.

Development of pH sensors integrated with the
microfluidic platform

• Development of the pH sensor together with the
  microfluidic part where the sensor is positioned.
• Development of materials, manufacturing steps,
  experiments and testing.

Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
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Three channels1mmx1mm each
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nanotechnologies
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1 channel flow
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3 channels flow
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2 mm x 2mm channels with enlarged areas (4
mmx2mm) hosting sensors and Cells (6mm exhaust)
Mesh
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Biomedical applications of micro and
nanotechnologies
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Flow analysis
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Flow analysis (details)
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Analysis of the flow rate by square section
channels
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Analysis of the flow rate by square section
channels (one active entry detail)
Bucharest, 6th of December
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Flow rate analysis considering a round shape of
the enlarged area hosting ITO electrode (three
entries in the exhaust channel)
Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
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Flow rate analysis considering a round shape of
the enlarged area hosting ITO electrode (detail)
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Flow rate analysis considering a round shape of
the enlarged area hosting ITO electrode (one
entry in the exhaust channel)
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Flow rate analysis considering a round shape of
the enlarged area hosting ITO electrode (one
entry in the exhaust channel) - detail
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
22
Flow rate analysis considering a round shape of
the enlarged area hosting ITO electrode
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
23
Flow rate analysis
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Technological flow microfluidic channels

• Material PDMS
• Patterning
• Laser machining
• Goal study, set-up and optimisation of the
  microfluidic channels issues design, technology,
  connections, integration into the platform

Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Microfluidic channels
Bucharest, 6th of December
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Biomedical applications of micro and
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Microfluidic channels
Bucharest, 6th of December
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Sensors cell
Sensors Unit
pH
Signal Processing Unit
Reference
Temperature sensor
Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
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Results

• Design of the microfluidic platform
• Study of sensors, materials, technological
  versions test structure utilisation
• Design of the sensors
• Interconnection layer design - draft

Bucharest, 6th of December
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Biomedical applications of micro and
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Biosensors for neurotoxic substances
detection The biosensors for neurotoxic
substances will be developed as ISFET-type
biosensors. The ISFET structure is represented by
a concentration-potential transducer, with a
biosensitive layer deposited on the gate
(Acetylcholinesterases, immobilised on
chitosane), which generates an interface
potential on the gate. The enzymatic ISFET
structure is developed in CMOS technology and the
sensors response characteristics depend mainly
on the AChE enzyme immobilisation mode.
Optical photography of the sensor chip
Bucharest, 6th of December
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Biomedical applications of micro and
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30
ISFET and chemoresistive sensors
Principle The change in conductivity at the
sensitive layer surface, deposited on top of the
sensor .
Characterisation
The enzyme electrode is a combination of any
electrochemical probe (amperometric,
potentiometric or conductometric) with a thin
layer (10?200mm) of immobilized enzyme. In these
devices, the function of the enzyme is providing
selectivity by virtue of its biological affinity
for a particular substrate molecule. For example,
an enzyme is capable of catalyzing a particular
reaction of a given substrate even though other
isomers of that substrate or similar substrates
may be present
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Bio integration
I. Surface Chemistry
Functionalization The silicon or glass
substrates are functionalized as hydrophobic,
hydrophilic, biocompatible surfaces Available
procedures Cleaning procedures Chemical Vapor
Deposition CVD, PSG, BPSG Polymer Adlayers
SU-8, Organosilanes (Rn-Si-X(4-n)) Passivation
(treatment in N2 and H2)
Immobilization technique
Ex After surface functionalization , the
immobilised AChE enzyme within a chitosan
biolayer laid on the sensor structure

Bucharest, 6th of December
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Biomedical applications of micro and
nanotechnologies
32
Field effect gas sensors Field effect gas
sensors are based on metal-insulator-semiconductor
structures used to detect chemical quantities.
Examples are biological and medical applications.
The surface field effect is a desirable
mechanism for a generating potential that
provides high chemical selectivity and
sensitivity. Using micromachining techniques we
manufactured an ISFET device with posibility of
integrating an area of sensing devices and the
electronics on the same chip ISFET sensors use
the field effect transistors to detect very small
quantities (10-3 g).
Simulation and Layout of a FET sensor on the
tip of a microprobe
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II. Deposition and characterization of biological
materials

• Deposition Plotter (OmniGrid Micro)
• Biological materials deposition for biosensors
  manufacturing

Immobilized enzyme on gold electrodes
Enzyme based biosensor
Characterization Scanner (GeneTAC UC4
Microarray scanner)
Enzyme based biosensor (fluorescence)
Bucharest, 6th of December
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nanotechnologies
34
III. Biosensors - Devices design and
fabrication including masks processing

• Microelectrodes to be deposited with
  biomaterials
• IMT can provide a wide range of microelectrodes
  design and manufacturing, for biomaterials
  applications. The microelectrodes can be
  deposited and configured on silicon substrates in
  our technological facilities.
• ISFET sensor for ions detection in biological
  media
• The surface field effect is a desirable mechanism
  for a generating potential that provides high
  chemical selectivity and sensitivity. The ISFET
  is essentially an extended gate field effect
  transistor with the surface of the transistor and
  the reference electrode.

Example of microelectrodes layout, for
biomaterials applications
ISFET sensor placed on a thin tip to be inserted
in small liquid media
Bucharest, 6th of December
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Biomedical applications of micro and
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35
Microfluidics devices development design,
simulations, manufacturing

• Design and simulations for microfluidics devices,
  including general flow, thermal, fluid mixing,
  electrokinetic, chemical reactions, etc.

Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies
36

• THANK YOU!
• The paper is presenting the result of two
  projects
• Toxichip, IST, STREP
• Toxisystem, Romanian Security Programme

Bucharest, 6th of December
Cooperation in FP7
Biomedical applications of micro and
nanotechnologies