---
res:
  bibo_abstract:
  - 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.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Christian
      foaf_name: Bippes, Christian A
      foaf_surname: Bippes
  - foaf_Person:
      foaf_givenName: Harald L
      foaf_name: Harald Janovjak
      foaf_surname: Janovjak
      foaf_workInfoHomepage: http://www.librecat.org/personId=33BA6C30-F248-11E8-B48F-1D18A9856A87
    orcid: 0000-0002-8023-9315
  - foaf_Person:
      foaf_givenName: Alexej
      foaf_name: Kedrov, Alexej
      foaf_surname: Kedrov
  - foaf_Person:
      foaf_givenName: Daniel
      foaf_name: Mueller, Daniel J
      foaf_surname: Mueller
  bibo_doi: 10.1088/0957-4484/18/4/044022
  bibo_issue: '4'
  bibo_volume: 18
  dct_date: 2007^xs_gYear
  dct_publisher: IOP Publishing Ltd.@
  dct_title: Digital force-feedback for protein unfolding experiments using atomic
    force microscopy@
...