Bioelectronics

Bioelectronics

The emerging field of “Bioelectronics” seeks to exploit biology in conjunction with electronics in a wider context encompassing, for example, biomaterials for information processing, information storage, electronic components and actuators.

Bioelectronics

Biomolecules and biological cells can, moreover, be used as the building blocks of higher-level functional devices for recognition or sensing within biosensors.

Bioelectronics research also seeks to use biomolecules to perform the electronic functions that semiconductor devices currently perform.

Bioelectronics

Research activities in both of the following general domains can be distinguished:

Micro/Nano-electronics for Life-Sciences, i.e. how micro/nano electronic systems can help to solve important problems in life sciences.Examples include integrated devices for detection of

cells, DNA, Proteins, and small molecules.

Bioelectronics

Life-Sciences for micro/nano electronic systems, i.e. how we can learn from nature to build micro and nano electronic devices.Examples include protein mediated electronic

devices and neuro-electronic circuitries.

Bioelectronics

One example of a key aspect in bioelectronics research is the interface between biological and electronic materials.

A major challenge in bioelectronics is the patterning of functional components and the interfacing with electrical components.

Bioelectronic interfaces

In the past few years, substantial progress has been made in understanding the interactions between cells and electronic substrates.

Monitoring the electrochemical activity of living cells with electronic sensors represents an emerging technique ranging from basic research in neuroelectronics to various fields of pharmacological analyses.

Electrochemical monitoring in cells

The realization of this approach requires several steps: development and fabrication of electronic

devices for the low noise registration of cellular signals

development and fabrication of electronic devices for the stimulation of cells, and

the effective coupling between the cellular systems and the electronic devices as well as the control over the cellular connections

Electrochemical monitoring in cells

Patterning extracellular matrix proteins and structured surfaces enables the controlled and selective adhesion and growth of cells onto chips, and the realization and investigation of cellular networks of controlled complexity and geometry

Bioelectronic interfaces

NANO AND MICROTECHNOLOGIES OF HYBRID BIOELECTRONIC SYSTEMS

Cell Patterning Approaches

• Direct protein lithography • Micro-contact printing/micro fluidics

• Proteins • SAMs

• Dry lithography• Patterned polymers• Temperature sensitive polymers• Nano-topography

• Ordered nano-patterning• Disordered nano-patterning

• Wells

Approaches (V) : Nanotopography

Ancient methodsMicro-methods

Silicon pillars Silicon grass

Nano-methods Carbon nanotubes

Approaches (V) : Nanotopography

Thermally grown SiO2

Resist

Exposure, development

RIE, CHF3: oxide etch

Photoresist removal

RIE: Cl2, BCl3 Si etch

HF: Oxide removal

Approaches (V) : Nanotopography

http://www.hgc.cornell.edu/neupostr/lrie.htm

Approaches (V) : Nanotopography

http://www.wadsworth.org/divisions/nervous/nanobio/DG06.htm

Approaches (V) : Nanotopography

Craighead

RIE: Cl2,CF4,O2

Photoresist

Wet etching: HF, nitric acid, H2O

Resist removal, Cleaning

Approaches (V) : Nanotopography

LRM55 Astroglial cells – prefer smooth surfacesCortical astrocytes – Preferred rough surface

Culture of neural cells on silicon wafers with nano-scale surface topograph Y.W. Fan et al, “Culture of neural cells on silicon wafers with nano-

scale surface topograph” : Si surfaces with variable roughness (without surface treatment)

-Morphology of adherent cells remarkably differs on differently rough surfaces

Cells and nanotopography

Cells respond to surface topography The mechanisms involving cell adhesion and

migration on surfaces is poorly understood Extremely important in the field of tissue engineering

and biomaterials Important in lab-on a chip/micro bio-sensors

Cells React to Nanoscale Order and Symmetry in

Their SurroundingsA. S. G. Curtis*, N. Gadegaard, M. J. Dalby, M. O. Riehle, C. D. W.

Wilkinson, and G. Aitchison

Methods

Arrays of nano-pits were prepared in a three-step process:

Electron Beam Lithography Nickel die fabrication Hot embossing into polymers

Cell Cultures

Primary human fibroblasts (connective tissue cells)/ rat epithenon cells were seeded on patterned PCL or PMMA

1. Short term experiments: measurements taken at intervals from 2-24 hr

2. Long term experiments: cells cultured for up to 71 days

Adhesion on spaced nanopatterened areas is much lower than on planar areas, but on the smallest closest spaced pits is the same as on the planar area!

Rat epitenon cells grown on PCL surfaces for 24 h

Human fibroblast cells grown on PCL

Many cells possess surface nanometric features

Filopodia and microspikes may be the organelle whosemajor function is to explore nanofeatures around the cell

It is interesting to note that the filopodia follows the nanopattern, and seems to be directed by it

Reaction of cells to different symmetries

Cathrine C. Berry et al, “The influence of microscale topography on fibroblast attachment and motility”:

fibroblasts were grown on arrays of pits, 7, 15 and 25 diameter, 20 and 40 mm spacing

1. Cells “prefer” entering the larger diameter pits, meaning they might be sensitive to differences in radius of curvature

2. The smallest pits allow the highest proliferation rate and the highest migration rate of a single cell

On orthogonal patterns :cells show preference of 90° separated orientations

On hexagonal patterns: cells show preference of 120° separated orientations

Orientation is nonrandom

Fredrick Johansson et al, “Axonal outgrowth on nano-imprinted patterns”

Investigated guidance of axons on patterns of parallel grooves of PMMA, with depths of 300nm, widths of 100-400 nm and distance between grooves 100-1600 nm.

-axons display contact guidance on all patterns-preferred to grow on edges and elevations in the

patterns rather than in grooves- this may be due to edge effects, as concentration of charges

What makes cells adhere to surfaces?

How cells sense ORDER and SYMMETRY of surfaces?

Why do differences in diameters and spacing of micro and nano features have such dramatic effect on cell adhesion?

Two possible explanations

The effect is caused by the nonliving surfaces aloneNanofeatures are known to affect orientations in nonliving systems

It is unknown whether nanofeatures affect protein adsorption on the nanoscale, (exposure to protein rich culture media- showed no difference)

The effect is caused by interaction of cellular processes and interfacial forces

Ordered conducting grooves

Rough conducting substrate

Random nano-topography insulating substrate

Ordered insulating grooves

Perturbed ordered insulating grooves

Nanofiber topography

Types of nano-topography

Carbon nanotube based neuro-chips for engineering and recording of cultured neural networks

Recording from cultured neural networksBen-Jacob, TAU Fromherz, MPIBauman, URosGross, UNT

Multi electrode arrays

E. Ben-Jacob

Large electrically active networks, Long term (weeks), Relevant biological activity

BUTLarge electrodes, Poor sealing, Average (many neurons) signal, Poor electrode-cell coupling, Random networks

Multi electrode arrays

How can we make better/new MEA

How do we manipulate cells on substrates?

Properties of our new MEAs

Cell-substrate interactions

Wong et al. Surface chemistry 2004

Nano-topography

Hu et al.Mattson et al.J. Mol. Neurosci 2000

Craighead, Cornell

Electronic properties (CNTs)

armchair

zigzag

Carbon nanotubes Biocompatible Super capacitors Compatibility with micro

fabrication

CNT electrodes Self-cell-organization Network engineering Excellent recording

Carbon nanotube multi-electrode arrays

CNT based MEAMo electrodes

SOG passivationRIE etch

PDMS stencilCNTs

Engineered Networks

Tension competes with adhesion to surface

Neuronal tissue on CNT electrodes

Electrical activity (CNTs)

Spontaneous electrical activity

Cell-surface interaction

Mo electrode

Craighead, Cornell

Summary

CNT are excellent substrates for neuronal growth

Self-organization of neuronsEngineered networksVery good recording properties

Approaches (V) : Topography

Peter Fromherz, Max Planck Institute

Approaches (V) : Topography

Fromherz (http://www.biochem.mpg.de/mnphys/)

CNT FET Bio-sensors

Approaches (V) : Topography

Approaches (V) : Topography

Approaches (VII) : Wells

Pine, Caltech

Approaches (VII) : Wells

Neuro-wells / neuro-cages

Space for neurite growth

Approaches (VI) : Wells

Some technical areas of opportunity for bioelectronics1. Real-time and massively parallel

molecular and cellular characterization for systems biology

2. Biologically-based sensors and fabrication

3. Protection and restoration of health

Challenges

In order to achieve necessary innovations in moving bioelectronics forward, experts in government agencies, academic research institutions, and industry will need to be coordinated and brought to bear in overcome cross-cutting challenges that stem from the lack of technology, biological understanding or a combination of both.

Challenges

Cellular and biomolecular measurements and analyses

FabricationDevice and material biocompatibilityPower sources