Category Archives: Sensors

Incubator for the electronics of the future – Rotronic Success Story

No extraneous sounds, vibrations or electromagnetic fields find their way into the noise-free lab at the Binnig and Rohrer Nanotechnology Center in Rüschlikon. Moreover, a temperature sensor ensures that experiments on new switching elements for computer chips are not affected by temperature fluctuations. 

Today, a single computer chip contains over a billion transistors, a far cry from the ten transistors in the first integrated circuit in 1958. In the intervening years, the structures have become so small that individual layers are just a few atoms thick. This has created a new problem of electrons flowing between layers. In order to prevent this from happening, researchers are endeavoring to reinvent the transistor and to explore new types of components.

The solution lies in silence 

Switzerland is home to a world-renowned laboratory in which scientists are working on the transistors of the future: the IBM research laboratory in Rüschlikon. The location’s easy accessibility is not exclusively advantageous: when a truck passes by, it causes the samples to shake under the electron microscope. In 2011, the Binnig and Rohrer Nanotechnology Center opened six integrated laboratories with exceptionally high protection against external factors: the noise-free labs. They are built directly on rock, the actual measurement set-ups mounted in turn on concrete blocks that float on a cushion of air. Forty-ton trucks can now race by without vibrating the sample. Another problem is noise. To keep it out, the labs are equipped with thick doors. Even the scientists present were too loud and were obliged to control the experiments from a separate room.

Precise room temperature

A temperature difference of just a few degrees would be capable of moving a sample by several 100 nanometres per hour with disastrous consequences for structures in the range of 1 – 50 nanometres. A sensor is therefore used to measure the temperature and air humidity. IBM is using a Rotronic transmitter capable of measuring temperature to 0.1 °C with absolute accuracy for this purpose. This corresponds to the maximum temperature drift permitted in the laboratory over a 1-hour period. At the same time, the sensor measures the relative humidity of the air which is required to remain within 35 and 55 %RH and not fluctuate by more than 5 %RH. The sensor is even capable of measuring the air humidity to exactly 0.8%RH thanks to an integrated chip.

Top-ranking labs

Researcher Heike Riel makes good use of the quantum effects to develop small transistors that are also highly energy efficient. Instead of an operating voltage of somewhat over 1 V commonly employed today, they would work with voltages of less than 0.5 V. Rolf Allenspach aims to utilized electron spin: spin-up corresponds to a logical 1, spin-down to a logical 0. The chief attraction of this is that much less energy is required to change the spin than to displace the electron as is the case in transistors today.

A relative humidity sensor for any application?

As we continue to measure relative humidity in more and more environments with ever increasing accuracy demands, we are pushing the humble capacitive humidity sensor into new realms.

Accuracy, drift, operating range and chemical resistance are key challenges for the relative humidity sensor industry. Our sensor experts work hard to develop new polymers and construction methods to ensure the best performance. At the same time advanced electronics and probe housings enable digital calibration and complex temperature corrections to further increase accuracy and performance. A final and often neglected part of ensuring a relative humidity probes performance is its filter. The correct filter ensures fast response and environmental protection. Filters also offer mechanical protection and eliminate damage caused by extreme airflow.

However understanding why sensors fail is often difficult to predict or understand. In many cases the chemicals and contaminants that sensors are exposed to are unknown. In these situations often selecting the best sensor can only be achieved through mutual relationships built around quality support and service.

In the UK we have worked closely with many customers and in combination with our Swiss technical divisions to select and develop solutions for some highly aggressive and challenging environments. Some of these projects are examined below in more detail.

Hydrogen peroxide vapour sterilisation.

– Hydrogen peroxide vapour is used to chemically sterilise environments and products by generating a vapour of toxic Hydrogen Peroxide. When the humidity reaches the dew point of the surfaces condensation forms sterilising all surfaces. However the chemicals are also highly aggressive to humidity sensors and constant cycles of saturation worsen the effects.

– Making use of Rotronic’s specifically designed H2O2 resistant sensor as well as additional conformal coating to protect exposed connections in further combination with improved customer understanding around handling and storage, has resulted in a solution that has exceeded customer expectations. Importantly, whilst this was not achieved first time around, through a partnership driven towards the end goal we achieved success.

Chemical damage Chemical degradation on the sensor surface
Commercial composting.

– Accelerated commercial composting is an impressive sight to see. The chemical and biological processes occurring are complex and surprisingly aggressive. The wrong materials can literally become part of the final compost if you are not careful. Chemically resistant sensors help to provide some longevity to instruments but one of the key areas requiring extra attention is around cable and filter design. Modifying a standard industrial grade sensor with bio-resilient cables ensures the probes are not eaten alive!

Highly accelerated life testing.

– As a supplier to many chamber manufacturers and companies providing testing services this is a common application. Chambers are cycled between high and low temperatures and humidities to simulate many years aging over a short period of time. The same effects are happening to the humidity sensor – critical for the control or validation of the chamber conditions. Using industrial sensors with electronics isolated away from chamber space reduces the effects of the sudden changes. But also care taken placing the sensor away from humidity outlets and well into the chamber to avoid stem conduction all help to avoid the sensor becoming saturated as temperature cycle – which is one of the main causes for corrosion and drift. Finally, careful filter maintenance is always important.

Swimming pool monitoring and control.

– Our featured image shows chemical formation on a non-Rotronic sensors connections. Rotronic uses inert metals in the sensor design to reduce the re-activity of the sensor to chemicals in the environments. Swimming pools have a mix of high humidity, chemicals and high temperatures which work together to corrode unprotected electronics. Sensor location is key to avoid direct exposure to spray and neat chemicals. Suitable filters and if required chemical resistant sensors have proven highly successful where other instruments have failed.

So you can see not all applications are easy and we have not even begun to explore the basic issues of accurate measurement and control present with every humidity sensor installation. However our belief and aim is that through communication and partnerships we can provide the right product to ensure the desired mix of performance, resilience and price for our customers – it’s not easy but it makes life interesting!

Dr. Jeremy Wingate

Rotronic UK