Publications by Olof Pontus Linderholm

Long-term in vivo impedance changes of subretinal microelectrodes implanted in dystrophic P23H rats

Retinal prostheses are being developed to restore vision in blind patients with photoreceptor degeneration. Electrodes arrays were subretinally implanted in transgenic P23H rats with their photoreceptors degenerated. Electrical stability of the implants wa ...

Wichtig Editore2013

Cell culture imaging using microimpedance tomography

Philippe Renaud, Olof Pontus Linderholm

We present a novel, inexpensive, and fast microimpedance tomography system for two-dimensional imaging of cell and tissue cultures. The system is based on four-electrode measurements using 16 planar microelectrodes (5 mum x 4 mm) integrated into a culture ...

2008

Characterization and optimization of liquid electrodes for lateral dielectrophoresis

Philippe Renaud, Harald Van Lintel, Nicolas Demierre, Urban Seger, Olof Pontus Linderholm, Thomas Michael Braschler

Using the concept of insulator-based "electrodeless" dielectrophoresis, we present a novel geometry for shaping electric fields to achieve lateral deviation of particles in liquid flows. The field is generated by lateral planar metal electrodes and is guid ...

2007

Bipolar resistivity profiling of 3D tissue culture

Philippe Renaud, Jonas Vannod, Yann Barrandon, Olof Pontus Linderholm

We describe a new low-cost technique for continuous monitoring of the thickness of biofilms and tissue cultures, and we demonstrate the advantage of using electrodes of different dimensions to probe different depths of a sample. We have used electric imped ...

Elsevier2007

Apparatus for manipulating, modifying and characterizing particles in a micro channel

Philippe Renaud, Nicolas Demierre, Urban Seger, Olof Pontus Linderholm, Thomas Michael Braschler

Microfluidic system comprising a space (0207) for containing a liquid and at least one lateral chamber (0201) in communication with said space, said lateral chamber containing a metal electrode (0204). The lateral chamber and the space are designed to be f ...

2007

Retinal Prosthesis : Testing Prototypes on a Dystrophic Rat Retina

Philippe Renaud, Olof Pontus Linderholm, Sri Harsha Kasi Raj

2007

Creating structures at the scale of cells on the fly: gentle single cell entrapment on chip

Philippe Renaud, Nicolas Demierre, Urban Seger, Olof Pontus Linderholm, Thomas Michael Braschler

2007

Two-dimensional impedance imaging of cell migration and epithelial stratification

Philippe Renaud, Jonas Vannod, Yann Barrandon, Olof Pontus Linderholm, Thomas Michael Braschler

We present a miniaturized impedance imaging system, developed for 2D imaging of cell and tissue culture. The system is based on 16 microelectrodes (5 µm × 4 mm). An equivalent circuit for four-point (tetrapolar) impedance spectra was developed and validate ...

2006

Subretinal electrode implantation in the P23H rat for chronic stimulations

Philippe Renaud, Olof Pontus Linderholm

Background: In age related macular degeneration and inherited dystrophies, preservation of retinal ganglion cells has been demonstrated. This finding has led to the development of various models of subretinal or epiretinal implant in order to restore visio ...

2006

Analytical expression for electric filed between two facing strip electrodes in microchannels

Philippe Renaud, Urban Seger, Olof Pontus Linderholm

An analytical solution is presented for the electric field between two facing strip electrodes situated in a microchannel, as frequently used in impedance cytometry applications. The measured change in resistance as induced by a 5 mm bead moving through th ...

2006

Two-dimensional microimpedance imaging for cell culture monitoring

Olof Pontus Linderholm

This thesis presents the fabrication and design of an impedance imaging sensor, and its application to monitoring in-vitro skin culture. Three-dimensional tissue cultures are becoming increasingly important in biological and medical research. There is, how ...

EPFL2006

Comment on AC frequency characteristics of coplanar impedance sensors as design parameters by Jongin Hong, Dae Sung Yoon, Sung Kwan Kim, Tae Song Kim, Sanghyo Kim, Eugene Y. Pak and Kwangsoo No, Lab Chip, 2005, 5, 270

Philippe Renaud, Olof Pontus Linderholm

In their article, ‘‘AC frequency characteristics of coplanar impedance sensors as design parameters’’, Hong et al.1 present an analytical model for the calculation of the resistance between two electrodes in a microchannel. However, their measurements fit ...

2005

Monitoring stem cell growth using a microelectrode array

Philippe Renaud, Yann Barrandon, Olof Pontus Linderholm

2005

An active microphotodiode array of oscillating pixels for retinal stimulation

Philippe Renaud, Mihai Adrian Ionescu, Olof Pontus Linderholm, Marco Mazza

We have developed an active microphotodiode array (MPDA) for retinal stimulation. The unique feature of the device is that each pixel acts as an independent oscillator, whose frequency is controlled by the incident light intensity. The design is based on a ...

2004

Microelectrical impedance tomography for biophysical characterization of thin film biomaterials

Philippe Renaud, Olof Pontus Linderholm, Reto Bruno Schoch

We present a new method for measuring the electrical resistivities of a stratified sample of thin biomaterials or tissue layers. The presented technique makes use of impedance measurements between It pairs of electrodes separated by varying distances. The ...

2003