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Posted: Jul 19, 2013

A new method for accurately measuring the bending of nanoscale components in diagnostic sensors

(Nanowerk News) A new method for accurately measuring the bending of nano and micron-sized components in diagnostic sensors, has been developed by researchers at the London Centre for Nanotechnology (LCN).
The method, published in the journal Applied Physics Letters ("Direct and alignment-insensitive measurement of cantilever curvature"), significantly simplifies the detection process, by enabling simultaneous measurement from an array of cantilevers. In doing so, the LCN technique can provide a solution to the challenging problem of multiplexed diagnostics.
Micro-cantilevers are one of the simplest and most common examples of micro systems technology. These devices are designed to respond to minute mechanical changes, and are routinely used in a range of different technologies, such as accelerometers in mobile phones and high-resolution microscopy.
Cantilever arrays can also be applied to a variety of diagnostic tests, including medical diagnostics, food safety, water quality or threat detection. The surface of each individual cantilever can be modified to detect a particular molecule, for example a specific antibody. As a target molecule attaches to the cantilever, it bends. This bending can be measured to confirm the molecule’s presence.
In current diagnostic systems utilising micro-cantilevers, the change in the state of a cantilever due to the presence of a target molecule is read by scanning and illuminating each cantilever individually. This introduces problems of alignment and can make the system sensitive to vibrations.
The LCN method removes the need to scan the beam, illuminating a whole cantilever array with a single, broad laser beam and recording a “picture” of the resulting diffraction pattern. The bending of the cantilever is revealed in greater detail, showing tilt, curvature, cubic and higher order bending. The highly accurate system is robust to misalignment as the qualities measured, such as size and shape, are independent to their position in the image.
The unique benefit of this approach is the simultaneous measurement of several markers (multiplexed detection), as for example in HIV diagnosis, where viral load and antibody concentrations could be obtained in one step using this method. The LCN has now designed and constructed a compact table-top prototype that incorporates this novel detection technique along with state of the art automatized fluid delivery system. It is thought that this technology has potential to be miniaturized at low cost, enabling future development of sophisticated point-of care devices
Dr. Rodolfo Hermans, lead author of the paper, said "Simple systems work every time and we have solved a detection problem by reducing the complexity of the hardware and therefore making it more reliable
The LCN method is the subject of a patent application filed in conjunction with UCL Business, the technology transfer office of UCL.
Source: London Centre for Nanotechnology
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