The surface forces apparatus (SFA) was developed in the late 1960s as a powerful tool for investigating molecular interactions across apposing surfaces including the first measurement of van der Waals forces and interactions in biologic and liquid media. However, the SFA has two major disadvantages. First, it traditionally uses white light interference between back-silvered muscovite mica surfaces to measure distances and to infer forces from distance shifts during interaction of two surfaces. Hence, distance shifts and force measurement are not decoupled. Second, productive SFA interferometers are so far limited to measuring across mica versus mica or mica versus metal. Direct gold-gold configurations were suggested in the late 1990s but not experimentally achieved as proof-of-principle until recently using a templating technique. In this work, we show how we solve these two disadvantages. First, we present a new SFA design that decouples force and distance measurements with similar resolution. The presented SFA design is inexpensive and can be home-built with mostly commercially available parts. Second, we present an alternative physical vapor deposition approach to construct a stable gold-gold interferometer and demonstrate its performance showing hydrophobic interactions, bubble formation, hemifusion of bilayers, and friction experiments. The presented system is easy to use. The obtained results show excellent reproducibility, indicating that the designed SFA and the three-mirror gold-gold interferometer functions as well as or even better than the traditional interferometer configurations used in SFA. This opens SFA to a wide range of options for various possible applications. Specifically, the gold-gold configuration allows a broad range of surface modifications for studying biophysical interactions as demonstrated in this work.

中文翻译：

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Novelin情景传感表面力仪器，用于测量金与金，疏水和生物物理相互作用

表面力装置（SFA）于1960年代后期开发，是研究跨相对表面的分子相互作用的强大工具，包括首次测量范德华力以及在生物和液体介质中的相互作用。但是，SFA有两个主要缺点。首先，传统上，它使用背面镀银白云母云母表面之间的白光干涉来测量距离，并根据两个表面相互作用期间的距离偏移来推断力。因此，距离偏移和力的测量不会分离。其次，到目前为止，生产型SFA干涉仪仅限于测量云母对云母或云母对金属。在1990年代后期提出了直接金-金构型，但直到最近才通过模板技术在实验上作为原理的证明而获得。在这项工作中，我们展示了如何解决这两个缺点。首先，我们提出了一种新的SFA设计，该设计可以以相似的分辨率将力和距离测量分离。提出的SFA设计价格便宜，并且可以使用大部分可商购的零件进行家庭建造。其次，我们提出了一种替代的物理气相沉积方法来构建稳定的金-金干涉仪，并证明其性能表现为疏水相互作用，气泡形成，双层半融合和摩擦实验。提出的系统易于使用。获得的结果显示出极好的可重复性，表明设计的SFA和三镜金金干涉仪的功能与SFA中使用的传统干涉仪配置相同甚至更好。这为各种可能的应用打开了SFA的多种选择。