High-speed Force Microscopy and Holo 4π AFM for Biological Systems
Event details
| Date | 31.08.2015 |
| Hour | 12:15 |
| Speaker | Prof. Mervyn Miles, University of Bristol (UK) |
| Location | |
| Category | Conferences - Seminars |
DISTINGUISHED LECTURE IN BIOLOGICAL ENGINEERING
(sandwiches served)
Abstract:
Atomic force microscopy (AFM) is complementary to many other microscopies in biological systems, and offers many benefits such has high-resolution 3D imaging in many environments including liquids. However, there are three areas in which conventional AFM has serious limitations: (i) a low imaging rate, (ii) the probe-sample force interaction, and (iii) the planar nature of the sample.
We are developing two high-speed force microscopy techniques to overcome the first two of these, (i) and (ii).
(i) One high-speed AFM (HS AFM) technique is a DC mode in which an automatic feedback mechanism, essentially arising from the hydrodynamics of the situation, maintains a tip-specimen separation of about 1 nm. This technique routinely allows video-rate imaging (30 frames per second, fps) and has achieved unprecedented imaging rates at over 1000 fps, i.e., 100,000 times faster than conventional AFM. Damage to specimens resulting from this high-speed DC-mode imaging is surprisingly less than would be caused at normal speeds. The behaviour of the cantilever and tip at these high velocities has been investigated and super lubrication is a key component in the success of this technique [1,2].
(ii) The other high-speed force microscope is a non-contact method based on shear-force microscopy (ShFM). In this HS ShFM, a vertically-oriented, laterally-oscillating probe detects the sample surface at about 1 nm from it as a result of the change in the mechanical properties of the water confined between the probe tip and the sample. With this technique, very low normal forces are applied to the specimen. There is a bonus of obtaining information on the structure of the molecular water layers as a function of position over the sample surface [3,4].
(iii) AFMs require planar samples because the probe scans in a plane. It is as if the tip is only ‘seeing’ the sample from above. We have overcome this limitation by steering the tip of a nanorod in a three dimensional scan with six degrees of freedom using holographically generated traps such that it is possible to scan around a sample from any direction. Various probe types have been utilized, including silica nanorods, rod-like diatoms, and custom designed, two-photon polymerized 3D structures [5,6].
1. Payton, OD, et al., Nanotechnology 23 (2012) Art. No. 265702.
2. Kalpetek, P, et al., Measurement Sci. & Technol., 24 (2013) Art. No. 025006.
3. Harniman RL, et al., Nanotechnology 23 (2012) Art. No. 085703.
4. Fletcher, J, et al., Science 340 (2013) online April 11th.
5. Phillips DB, et al., Nanotechnology 22 (2011) Art. No. 285503.
6. Olof SN et al., Nano Letters 12 (2012) 6018-6023.
Bio:
About the speaker: Dr. Mervyn Miles is Professor of Physics and Head of the Nanophysics and Soft Matter Group at the University of Bristol (UK), Fellow of the Royal Society and holder of the Royal Society Wolfson Research Merit Award.
Dr. Miles is distinguished for the development of a number of revolutionary new techniques of scanning-probe microscopy and demonstrating their potential for breaking into new areas of research in the study of biomolecular and polymer systems. One of these permits, for the first time, the study of dynamic changes in many systems of critical interest achieved through imaging rates of more than 100 frames per second, fast enough to follow previously inaccessible biomolecular processes and to fabricate nanoscale structures. A second is a unique form of force microscopy that senses the specimen surface through a few atomic layers of water molecules without mechanical contact, ideal for studying delicate biological structures at high resolution. A third involves adjustment of the damping of an atomic force cantilever in a liquid environment so as to improve sensitivity, significantly enhancing the rate of imaging and reducing the damage caused to soft materials.
Keywords applying to research in the Miles Lab:
Atomic force microscopy, scanning tunnelling microscopy, scanning near-field optical microscopy, high-speed AFM, high-speed non-contact AFM, holographic optical tweezer, optical AFM, polymers, biomolecules
(sandwiches served)
Abstract:
Atomic force microscopy (AFM) is complementary to many other microscopies in biological systems, and offers many benefits such has high-resolution 3D imaging in many environments including liquids. However, there are three areas in which conventional AFM has serious limitations: (i) a low imaging rate, (ii) the probe-sample force interaction, and (iii) the planar nature of the sample.
We are developing two high-speed force microscopy techniques to overcome the first two of these, (i) and (ii).
(i) One high-speed AFM (HS AFM) technique is a DC mode in which an automatic feedback mechanism, essentially arising from the hydrodynamics of the situation, maintains a tip-specimen separation of about 1 nm. This technique routinely allows video-rate imaging (30 frames per second, fps) and has achieved unprecedented imaging rates at over 1000 fps, i.e., 100,000 times faster than conventional AFM. Damage to specimens resulting from this high-speed DC-mode imaging is surprisingly less than would be caused at normal speeds. The behaviour of the cantilever and tip at these high velocities has been investigated and super lubrication is a key component in the success of this technique [1,2].
(ii) The other high-speed force microscope is a non-contact method based on shear-force microscopy (ShFM). In this HS ShFM, a vertically-oriented, laterally-oscillating probe detects the sample surface at about 1 nm from it as a result of the change in the mechanical properties of the water confined between the probe tip and the sample. With this technique, very low normal forces are applied to the specimen. There is a bonus of obtaining information on the structure of the molecular water layers as a function of position over the sample surface [3,4].
(iii) AFMs require planar samples because the probe scans in a plane. It is as if the tip is only ‘seeing’ the sample from above. We have overcome this limitation by steering the tip of a nanorod in a three dimensional scan with six degrees of freedom using holographically generated traps such that it is possible to scan around a sample from any direction. Various probe types have been utilized, including silica nanorods, rod-like diatoms, and custom designed, two-photon polymerized 3D structures [5,6].
1. Payton, OD, et al., Nanotechnology 23 (2012) Art. No. 265702.
2. Kalpetek, P, et al., Measurement Sci. & Technol., 24 (2013) Art. No. 025006.
3. Harniman RL, et al., Nanotechnology 23 (2012) Art. No. 085703.
4. Fletcher, J, et al., Science 340 (2013) online April 11th.
5. Phillips DB, et al., Nanotechnology 22 (2011) Art. No. 285503.
6. Olof SN et al., Nano Letters 12 (2012) 6018-6023.
Bio:
About the speaker: Dr. Mervyn Miles is Professor of Physics and Head of the Nanophysics and Soft Matter Group at the University of Bristol (UK), Fellow of the Royal Society and holder of the Royal Society Wolfson Research Merit Award.
Dr. Miles is distinguished for the development of a number of revolutionary new techniques of scanning-probe microscopy and demonstrating their potential for breaking into new areas of research in the study of biomolecular and polymer systems. One of these permits, for the first time, the study of dynamic changes in many systems of critical interest achieved through imaging rates of more than 100 frames per second, fast enough to follow previously inaccessible biomolecular processes and to fabricate nanoscale structures. A second is a unique form of force microscopy that senses the specimen surface through a few atomic layers of water molecules without mechanical contact, ideal for studying delicate biological structures at high resolution. A third involves adjustment of the damping of an atomic force cantilever in a liquid environment so as to improve sensitivity, significantly enhancing the rate of imaging and reducing the damage caused to soft materials.
Keywords applying to research in the Miles Lab:
Atomic force microscopy, scanning tunnelling microscopy, scanning near-field optical microscopy, high-speed AFM, high-speed non-contact AFM, holographic optical tweezer, optical AFM, polymers, biomolecules
Practical information
- Informed public
- Free