Search

Background: To date, biological components have been incorporated into MEMS devices to create cell-based sensors and assays, motors and actuators, and pumps. Bio-MEMS technologies present a unique opportunity to study fundamental biological processes at a level unrealized with previous methods. The capability to miniaturize analytical systems enables researchers to perform multiple experiments in parallel and with a high degree of control over experimental variables for high-content screening applications. Methodology/Principal Findings: We have demonstrated a biological microelectromechanical system (BioMEMS) based on silicon cantilevers and an AFM detection system for studying the physiology and kinetics of myotubes derived from embryonic rat skeletal muscle. It was shown that it is possible to interrogate and observe muscle behavior in real time, as well as selectively stimulate the contraction of myotubes with the device. Stress generation of the tissue was estimated using a modification of Stoney's equation. Calculated stress values were in excellent agreement with previously published results for cultured myotubes, but not adult skeletal muscle. Other parameters such as time to peak tension (TPT), the time to half relaxation (KRT) were compared to the literature. It was observed that the myotubes grown on the BioMEMS device while generating stress magnitudes comparable to those previously published, exhibited slower TPT and KRT values. However, growth in an enhanced media increased these values. From these data it was concluded that the myotubes cultured on the cantilevers were of an embryonic phenotype. The system was also shown to be responsive to the application of a toxin, veratridine., Pub. in PloS One, v5 n6, p1-11, June 2010.

The present invention is a method and apparatus for detecting a target species. The target molecule may be in liquid phase (in solution) or (for some embodiments of the invention) in vapor phase. A sensor according to the present invention monitors whether a target species has selectively bound to groups on the cantilever surface by monitoring the displacement of the cantilever, and hence the force acting on the cantilever. This force acting on the cantilever arises from the force acting on a structure that moves in electric or magnetic field, and that may be selectively bound to the cantilever. In the case of target species having a sufficiently large net electric charge or dipole moment, the target species itself may serve as the structure that moves in an electric field. More typically however, separate modified structures, such as modified magnetic beads or modified beads having a net charge or a dipole moment, will, when selectively bound to the cantilever, exert a force on the cantilever that relates to the presence of the target species., Supersedes PAT-APPL-505 547-95, AD-D017 845.

The magnetic sensor of this invention is characterized by a magnet suspended on a torsion bar or wire and by a tunneling tip separated from one end of the magnet, a gap between the tip and the magnet that is small enough to support a tunneling current, an electrical source for imposing a constant biasing voltage across the gap, an electrical force to maintain the magnet and the tip sufficiently close so that a constant tunneling current is maintained therebetween, a feedback circuit to monitor current changes in the gap that result from rotation of the magnet due to changes in the surrounding magnetic field and at least one recorder to record changes in the magnetic field. The method for detecting rotation of a magnet by a sensor caused by a change in the surrounding magnetic field includes the steps of biasing tunneling tip and a magnet with respect to each other, positioning the tip and/or magnet so there is a tunneling current therebetween, adjusting width of the tunneling gap to establish a constant tunneling current therebetween, exposing the magnet to a magnetic field that causes the magnet to rotate and to change the width of the gap, adjusting the width of the gap to reestablish a constant tunneling current in the gap, and recording the change in the feedback control voltage which is proportional to the change in the magnetic field., Supersedes PAT-APPL-193-690-94, AD-D016 227.

A method and apparatus to use an Atomic Force Microscope to take measurements of surface forces, indentation, adhesion and mechanical properties such as hardness and elasticity. The force between a probe mounted cantilever and a sample is measured as a function cantilever deflection measured by a electron tunneling microscope. The sample and the tip of the tunneling microscope are each mounted on piezoelectric manipulators which provide for position control. Position of the sample and probe are measured from the voltages applied to the piezoelectric manipulators. Penetration is determined by the relative motion between the probe and sample. Presently, this invention has a force resolution of 1 nN and a depth resolution of 0.02 nm., Supersedes PAT-APPL-560 391-90.

A sensor for ultra-low concentration chemical recognition comprises a force transducer, a tip coupled to this force transducer, and a substrate positioned for force interaction with the force transducer tip, where the substrate and tip are chemically modified so that there is a specific force interaction between the tip and the substrate in the presence of the target species, and a measurably different force interaction in the absence of the target species.

A tunneling tip piezo is incorporated into various devices for measuring the effect of changes in environmental conditions (i.e., temperature, pressure, magnetic and electrical fields, etc) upon a material by sensing minute changes in the dimensions of the surface. The devices may be used to detect changes in environmental conditions or to determine physical properties of a material. (Author), Supersedes PAT-APPL-484 950-90, AD-D014 580.