{"citation":{"ieee":"C. Bippes, H. L. Janovjak, A. Kedrov, and D. Mueller, “Digital force-feedback for protein unfolding experiments using atomic force microscopy,” <i>Nanotechnology</i>, vol. 18, no. 4. IOP Publishing Ltd., 2007.","short":"C. Bippes, H.L. Janovjak, A. Kedrov, D. Mueller, Nanotechnology 18 (2007).","mla":"Bippes, Christian, et al. “Digital Force-Feedback for Protein Unfolding Experiments Using Atomic Force Microscopy.” <i>Nanotechnology</i>, vol. 18, no. 4, IOP Publishing Ltd., 2007, doi:<a href=\"https://doi.org/10.1088/0957-4484/18/4/044022\">10.1088/0957-4484/18/4/044022</a>.","ama":"Bippes C, Janovjak HL, Kedrov A, Mueller D. Digital force-feedback for protein unfolding experiments using atomic force microscopy. <i>Nanotechnology</i>. 2007;18(4). doi:<a href=\"https://doi.org/10.1088/0957-4484/18/4/044022\">10.1088/0957-4484/18/4/044022</a>","apa":"Bippes, C., Janovjak, H. L., Kedrov, A., &#38; Mueller, D. (2007). Digital force-feedback for protein unfolding experiments using atomic force microscopy. <i>Nanotechnology</i>. IOP Publishing Ltd. <a href=\"https://doi.org/10.1088/0957-4484/18/4/044022\">https://doi.org/10.1088/0957-4484/18/4/044022</a>","ista":"Bippes C, Janovjak HL, Kedrov A, Mueller D. 2007. Digital force-feedback for protein unfolding experiments using atomic force microscopy. Nanotechnology. 18(4).","chicago":"Bippes, Christian, Harald L Janovjak, Alexej Kedrov, and Daniel Mueller. “Digital Force-Feedback for Protein Unfolding Experiments Using Atomic Force Microscopy.” <i>Nanotechnology</i>. IOP Publishing Ltd., 2007. <a href=\"https://doi.org/10.1088/0957-4484/18/4/044022\">https://doi.org/10.1088/0957-4484/18/4/044022</a>."},"date_created":"2018-12-11T12:04:50Z","month":"01","status":"public","year":"2007","publisher":"IOP Publishing Ltd.","day":"31","date_published":"2007-01-31T00:00:00Z","volume":18,"publist_id":"2501","date_updated":"2021-01-12T07:51:46Z","type":"journal_article","extern":1,"intvolume":"        18","author":[{"last_name":"Bippes","full_name":"Bippes, Christian A","first_name":"Christian"},{"orcid":"0000-0002-8023-9315","first_name":"Harald L","full_name":"Harald Janovjak","id":"33BA6C30-F248-11E8-B48F-1D18A9856A87","last_name":"Janovjak"},{"full_name":"Kedrov, Alexej","first_name":"Alexej","last_name":"Kedrov"},{"full_name":"Mueller, Daniel J","first_name":"Daniel","last_name":"Mueller"}],"doi":"10.1088/0957-4484/18/4/044022","_id":"3727","title":"Digital force-feedback for protein unfolding experiments using atomic force microscopy","quality_controlled":0,"publication_status":"published","issue":"4","publication":"Nanotechnology","abstract":[{"lang":"eng","text":"Since its invention in the 1990s single-molecule force spectroscopy has been increasingly applied to study protein (un-)folding, cell adhesion, and ligand–receptor interactions. In most force spectroscopy studies, the cantilever of an atomic force microscope (AFM) is separated from a surface at a constant velocity, thus applying an increasing force to folded bio-molecules or bio-molecular bonds. Recently, Fernandez and co-workers introduced the so-called force-clamp technique. Single proteins were subjected to a defined constant force allowing their life times and life time distributions to be directly measured. Up to now, the force-clamping was performed by analogue PID controllers, which require complex additional hardware and might make it difficult to combine the force-feedback with other modes such as constant velocity. These points may be limiting the applicability and versatility of this technique. Here we present a simple, fast, and all-digital (software-based) PID controller that yields response times of a few milliseconds in combination with a commercial AFM. We demonstrate the performance of our feedback loop by force-clamp unfolding of single Ig27 domains of titin and the membrane proteins bacteriorhodopsin (BR) and the sodium/proton antiporter NhaA."}]}