Optical Atomic Force Microscopy

原子力显微镜（AFM）是一种最先进的成像系统，它使用锋利的探针在物体表面来回扫描。探针尖端可以具有原子尺寸，这意味着AFM可以以近原子分辨率对物体表面进行成像。然而，这些系统的局限性在于，就像唱片机一样，针必须由机械臂或悬臂保持。这限制了对样品的接触，并阻止了对深通道或任何非水平表面的探测。我们的想法是将AFM的针尖固定在光束中，而不受任何机械约束。光镊利用光束的动量来捕获和移动单个球体，在这里我们将使用它们来固定和控制AFM针尖-而不需要任何机械固定。我们已经展示了使用数据投影仪技术来塑造光束以固定许多物体，这可以控制一个简单的探针。我们还表明，高速相机可以测量作用在探针上的力，其灵敏度比大多数AFM高100倍。最后，我们已经表明，光学镊子的界面可以变得直观，例如通过iPhone或力反馈操纵杆控制！在这个项目中，我们将开发我们使用的视频游戏图形卡的高速控制和力反馈，给用户一个触觉界面，也许利用专业相当于一个Wii的运动控制器。我们将自动化全三维扫描系统，以便获得完整的表面图像。我们将创建新的探头类型，功能化以提供各种对比度增强。最初，我们的图像将是标准的AFM测试样品，但除了这个基准，我们已经预算由领先的生物物理研究人员访问，以测试我们的新方法在他们的真实的应用。这些范围从细胞与细胞的相互作用到单个干细胞的分化。该项目雄心勃勃，在光镊、原子力显微镜和成像技术方面开辟了新天地，但合作团队的记录证明了该项目的成功。

Atomic force microscopy (AFM), is a state-of-the-art imagining system that uses a sharp probe to scan backwards and forwards over the surface of an object. The probe tip can have atomic dimensions, meaning that AFM can image the surface of an object at near atomic resolution. However, the limitation of these systems is that, just like with a record player, the needle has to be held by a mechanical arm or cantilever. This restricts the access to the sample and prevents the probing of deep channels or indeed any surface that isn't predominantly horizontal.Our idea is to hold the tip of an AFM in an optical beam, without any mechanical constraint. Optical tweezers use the momentum of light beams to trap and move individual spheres, here we will use them to hold and control the AFM tip - without need for any mechanical fixing.We have shown the use of data-projector technology to shape light beams to hold many objects, and that this can give control over a simple probe. We have also shown that high-speed cameras can measure the force acting on the probe with 100 times greater sensitivity than most AFMs. Finally we have shown that the interface of optical tweezers can be made intuitive, e.g. controlled by iPhone or force-feedback joystick!In this project we will develop our use of video game graphics cards for high-speed control and force-feedback to give the user a tactile interface, perhaps utilising the professional equivalent of a Wii motion controller. We will automate a fully-3D scanning system so that complete surface images will be obtained. We will create new probe types, functionalised to give various contrast enhancements. Initially our images will be of standard AFM test samples, but beyond this benchmarking we have budgeted for visits by leading biophysical researchers to test our new approach in their real applications. These range from cell-to-cell interactions to the differentiation of single stem cells.The project is ambitious breaking new ground in optical tweezers, AFM and imaging technologies, but the track records of the collaborating teams lend credence to the success of this project.