TEKNIK ELEKTRONIKA

Researchers from Delft University of Technology (Netherlands) and the Foundation for Fundamental Research on Matter have produced a design for the smallest electric motor in the world. The motor consists of just a single molecule and is not fuelled by light or heat (as is the case for previous designs), but by an electric field. As the field can be applied locally, it is possible to power just a single molecule. The speed of the motor can be accurately controlled by adjusting the frequency of the electric field. In principle, speeds to in the GHz range should be possible. The findings were published recently in ACS Nano.

 

The motor consists of a molecule that is placed above a gate-electrode and clamped between two gold electrodes. The central part of the molecule, the rotor, has a dipolar moment. The rotor can be set in motion by applying an alternating voltage across the gate. One of the greatest challenges of molecular motors is detecting the rotation, especially if it concerns a single molecule. The proposed motor uses the sensitivity of the resistance to determine the rotor position. At rest, the resistance is low. However, if the rotor rotates with respect to the rest of the molecule then the resistance shoots up. This makes it possible to measure the movement of the motor in real time.

 

For the time being the motor is only a concept, although certain aspects of the design have been experimentally confirmed. Calculations reveal that it should be possible to fuel and measure the proposed motor using existing measurement set-ups. The researchers are now working hard on realising the design. Possible applications are still a long way off, but include pump-like transport mechanisms similar to those found in the membranes of living cells.

 

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Paper: An All-Electric Single-Molecule Motor', ACS Nano 2010, 4 (11)



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Plessey Semiconductors and the University of Sussex have unveiled an innovative technology for contactless sensing of electric potentials. Using a device dubbed the electric potential sensor (EPS), this technology is able to sense changes in electric fields in the same way as a magnetometer detects changes in magnetic fields.

 

The new sensor, which does not need any physical or resistive contact to make measurements, will enable innovative new products such as medical scanners that are simply held close to a patient’s chest to obtain a detailed ECG or devices that can sense objects through walls. The initial application areas for EPS will be in medical treatment and sports, since the EPS device can detect voltage changes in muscles and nerves without direct electrical contact.
 
Until recently, electric fields have usually been measured either with relatively insensitive detectors operating in the range of several hundred volts to check for potential electrostatic discharges that might damage sensitive equipment, or with large laboratory electrometers that require frequent recalibration. The University of Sussex has solved the recalibration issue with a patented combination of techniques that prevent the accumulation of electrostatic charge and avoid electrostatic damage, making the new EPS technology intrinsically stable.
 
The EPS device operates at normal room temperatures and acts as highly stable, extremely sensitive and ultra high-impedance contactless electric field strength sensor for measurements down to the millivolt level. Most places on Earth have a vertical electric field strength of around 100 volts per metre. The human body is mostly water and interacts with this electric field. EPS technology is so sensitive that it can detect these changes at a distance, even through a solid wall. For example, in a burning building it could be used to determine whether any people are present in a smoke-filled room before opening the door.
 
Image: Plessey Semiconductors

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Plessey Semiconductors website



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writes that Joules came from a challenge to build an electric tandem bicycle powered by actually pushing the pedals like a person. Fun kinetic design was part of the intent, practicality was not. Riding with Joules is a reminder that engineering and craftsmanship can be joyful pursuits. Engineering and art need not be separate.

The designer hopes that  Joules can remind kids that creating real things is great way to spend time, and perhaps a career. Joules sits on the back of a tandem bicycle and does all of the pedaling.
A fun part of making Joules was creating a mechanism that mimics human pedaling. The kinetics of it turned out to be interesting to watch.

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