Queen's University in Canada
selects Linkam temperature stages
to characterize ferroelectric liquid crystals

Market leaders in temperature controlled microscopy, Linkam Scientific Instruments, have been used as temperature stage suppliers to Queen's University in Canada for ten years to study the properties of ferroelectric liquid crystals.

The research program of Professor Robert Lemieux and his Kingston, Ontario- based team focuses on the rational design of chiral and achiral molecular components of ferroelectric liquid crystal mixtures based on principles of self-assembly and molecular recognition.

Understanding the thermal properties of liquid crystals is crucial to the establishment of structure-property relationships that are useful in the design of new materials with improved properties. For example, in the design of 'de Vries-like' liquid crystals, the focus is on changes occurring at the SmA-SmC phase transition, both in terms of the order of the phase transition as well as changes in physical properties such as birefringence. As such, the use of thermal polarized optical microscopy allows the observation of texture changes at the SmA-SmC phase transition that provides useful information on such changes, and the Linkam LTS-350 hot stage used provides precise temperature control for this purpose.

The design of the LTS-350 hot stage also makes possible the integration of thermal polarized optical microscopy with the automated Liquid Crystal Analysis System (LCAS-1) by LC Vision in a convenient, turn-key fashion. This is used to measure the spontaneous polarization and optical tilt angle of ferroelectric SmC* liquid crystals induced by a variety of chiral dopants. These measurements are normally performed as a function of temperature using the LTS-350 hot stage.

The Linkam Liquid Crystal Pro system is in use by scientists all over the world. Leading academic and industrial research scientists have made the LTSE350 their preferred choice because of the high degree of control of heating rates, accuracy and long term stability for temperature controlled studies using light microscopes and other spectrometer platforms. It is optimised for liquid crystal sample analysis having fast heating rates up to 30°C/min and excellent thermal stability over the range from -196°C to 350°C. The stage consists of a large area temperature controlled element with a 100 Ohm platinum resistor sensor embedded close to the surface for accurate temperature measurements. It may be operated with Linksys32 DV Imaging software and a QICAM digital camera to provide fully indexed images at predefined points in the temperature profile. For a completely integrated solution, the system can be used with the Linkam Imaging Station to provide an ergonomic platform for easy sample handling without the need for a stand-alone optical microscope.

For further information, about the broad range of applications in the field of temperature controlled microscopy, and their range of LCAS family of characterization tools, view website: www.lc-vision.com   Refer to next page

ForceRobot®300 system for single molecule force spectroscopy studies

JPK Instruments, a world-leading manufacturer of nanoanalytic instrumentation for research in life sciences and soft matter, recently launched its latest member of their nanotechnology characterization systems family: the ForceRobot®300, the new standard in single molecule force spectroscopy. (Refer to picture on the left).

Force spectroscopy is a single molecule technique that allows the real-time study of molecular interactions on the nanoscale. Originating from the broad field of Atomic Force Microscopy (AFM), force spectroscopy directly addresses the measurement of forces between and within molecules. The sensitivity is high enough to characterize molecular interactions such as the unfolding forces of single proteins or forces of a single molecular bond.

The key to obtaining meaningful results from single molecule techniques such as force spectroscopy is the statistical management of the results. This is where the new ForceRobot®300 technology delivers the solution. The automated setup and continuous adjustments provide improvements in the efficiency of data collection while the integration of optical techniques allows targeted measurements where the molecules of interest are located. These factors, combined with the highest data quality and stability, open the field of single molecule force spectroscopy to a new level of results.

Until now, single molecule force spectroscopy was a complicated procedure. The requirement of frequent manual calibrations and alignments as well as the need for constant operator presence with the instrument made it a long-winded task. Useful data output was both low and slow with only a few suitable curves obtained over many hours. The ForceRobot®300 addresses these issues as a dedicated tool for the force spectroscopist.

The key to the system is the incorporation of intelligent software for experimental design, data acquisition and evaluation. Tens of thousands of force curves may be generated and evaluated in a matter of hours. To produce high quality curves requires an exceptional instrument with the lowest noise floor and the most rigid mechanical design. The highest accuracy and stability of the instrument is ensured by integrated capacitive position sensors with drift being minimized thorough utilizing a symmetrical system design.

The system may be operated in a stand-alone mode (see photograph) to give maximum access and flexibility to the sample. Alternatively, it may be mounted on top of an inverted optical microscope to enable simultaneous force spectroscopy and fluorescence microscopy. Both versions are available with a choice of positioning stage. While the basic motorized stage will provide positioning to better than one micron, the Precision Mapping Stage uses closed-loop control with noise levels to better than 0.3nm with positioning to about 1nm.

Like all JPK's advanced instruments, the ForceRobot®300 has many further options for fluidics and temperature control to enable the most reproducible results. To learn more, download a brochure and read about various applications, view website: www.jpk.com or e-mail: dammermann@jpk.com

JPK have added new electrochemical
capabilities to their NanoWizard AFM systems

Electrochemical experiments study redox reactions of substances at a solid-liquid interface. With atomic force microscopy, high-resolution images can be obtained in liquid as the electrochemical reaction progresses.  Electrochemistry spans a wide range of fields, from the corrosion of metal surfaces through to the role of protein electron transfer processes in biosensors. The new JPK ECCell™ enables simultaneous AFM and electrochemistry with full environmental control. Uniquely, the cell enables simultaneous fluorescence experiments to be carried out when the JPK NanoWizard® AFM is operated on inverted optical microscopes.

Refer to picture: The JPK ECCell™, is suitable for NanoWizard® and NanoWizard® II AFM heads. The cell is shown together with the temperature controller unit.

The key challenge for the electrochemical cell design is to integrate the many components and control elements within a small volume around the AFM tip.  This has been successfully achieved with the JPK ECCell™, which offers the complete electrode set of working electrode, counter electrode and commercial reference electrode, together with an optional tip bias connection, for instance, for scanning electrochemical microscopy (SECM).  The three fluid inlets allow liquid exchange during the measurements as well as gas exchange over the liquid in the chamber for inert gas experiments in an oxygen-free environment.  The temperature control unit gives precise temperature stability from room temperature to 60 °C in aqueous solutions.

The ECCell™ is compatible with a wide range of opaque or transparent samples, including standard coverslips, metal, or silicon chips.  It can be used for simultaneous optical experiments if the sample is transparent. For example, ITO-coated coverslips allow conductive measurements simultaneously with high numerical aperture immersion objectives. The mechanical stability ensures that simultaneous high-resolution AFM imaging is possible. This allows exciting new experiments where the optical microscope is used to simultaneously observe the sample.  For instance, living cells can be monitored on Multi-Electrode Arrays (MEAs), or fluorescence can be used to see electrochemical changes or switching of surface molecules.

Electrochemistry applications are extensive.  Corrosion of metal surfaces is a well-established field with obvious economic as well as scientific interest.  In many devices, electrically active or reactive polymer substances have an increasing role and significance as both, bulk materials and thin films. 

In addition, electrochemistry is a powerful tool in biochemistry to study proteins undergoing or catalyzing redox reactions.  Proteins in the lipid membrane enclosing living cells are sensitive to and control the potential difference across the membrane, for instance the ion channels in neuron cells.

To learn more about applications for the JPK ECCell™ capability, view website: www.jpk.com

JPK Instruments AG in profile
JPK Instruments AG is a world-leading manufacturer of nanoanalytic instruments - particularly atomic force microscope (AFM) systems and optical tweezers - for a broad range of applications reaching from soft matter physics to nano-optics, from surface chemistry to cell and molecular biology. JPK was recognized as Germany's fastest growing nanotechnology company in 2007 and 2008 (Deloitte). From its earliest days applying atomic force microscope (AFM) technology, JPK has recognized the opportunities provided by nanotechnology for transforming life sciences and soft matter research. This focus has driven JPK's success in uniting the worlds of nanotechnology tools and life science applications by offering cutting-edge technology and unique applications expertise.  Headquartered in Berlin and with direct operations in Dresden, Cambridge (UK) and Singapore, JPK maintains a global network of distributors and support centers and provides on the spot applications and service support to an ever-growing community of researchers.

For further information, view website: www.jpk.com or e-mail: dammermann@jpk.com   Refer to page 228