(Press-News.org) Humans have been inspired by nature since the beginning of time. We mimic nature to develop new technologies, with examples ranging from machinery to pharmaceuticals to new materials. Planes are modelled on birds and many drugs have their origins in plants. Researchers at the Department of Mechanical and Process Engineering have taken it a step further: in order to develop an extremely sensitive temperature sensor they took a close look at temperature-sensitive plants. However, they did not mimic the properties of the plants; instead, they developed a hybrid material that contains, in addition to synthetic components, the plant cells themselves. "We let nature do the job for us," explains Chiara Daraio, Professor of Mechanics and Materials.
The scientists were able to develop by far the most sensitive temperature sensor: an electronic module that changes its conductivity as a function of temperature. "No other sensor can respond to such small temperature fluctuations with such large changes in conductivity. Our sensor reacts with a responsivity at least 100 times higher compared to the best existing sensors," says Raffaele Di Giacomo, a post-doc in Daraio's group.
Water is replaced by nanotubes
It has been known for decades that plants have the extraordinary ability to register extremely fine temperature differences and respond to them through changes in the conductivity of their cells. In doing so, plants are better than any man-made sensor so far.
Di Giacomo experimented with tobacco cells in a cell culture. "We asked ourselves how we might transfer these cells into a lifeless, dry material in such a way that their temperature-sensitive properties are preserved," he recounts. The scientists achieved their objective by growing the cells in a medium containing tiny tubes of carbon. These electrically conductive carbon nanotubes formed a network between the tobacco cells and were also able to penetrate the cell walls. When Di Giacomo dried the nanotube-cultivated cells, he discovered a woody, firm material that he calls 'cyberwood'. In contrast to wood, this material is electrically conductive thanks to the nanotubes, and interestingly the conductivity is temperature-dependent and extremely sensitive, just like in living tobacco cells.
Touchless touchscreen and heat-sensitive cameras
As demonstrated by experiments, the cyberwood sensor can identify warm bodies even at distance; for example, a hand approaching the sensor from a distance of a few dozen centimetres. The sensor's conductivity depends directly on the hand's distance from the sensor.
According to the scientists, cyberwood could be used in a wide range of applications; for instance, in the development of a 'touchless touchscreen' that reacts to gestures, with the gestures recorded by multiple sensors. Equally conceivable might be heat-sensitive cameras or night-vision devices.
Thickening agent pectin in a starring role
The ETH scientists, together with a collaborator at the University of Salerno, Italy, not only subjected their new material's properties to a detailed examination, they also analysed the origins of their extraordinary behaviour. They discovered that pectins and charged atoms (ions) play a key role in the temperature sensitivity of both living plant cells and the dry cyberwood. Pectins are sugar molecules found in plant cell walls that can be cross-linked, depending on temperature, to form a gel. Calcium and magnesium ions are both present in this gel. "As the temperature rises, the links of the pectin break apart, the gel becomes softer, and the ions can move about more freely," explains Di Giacomo. As a result, the material conducts electricity better when temperature increases.
The scientists submitted a patent application for their sensor. In ongoing work, they are now further developing it such that it functions without plant cells, essentially with only pectin and ions. Their goal is to create a flexible, transparent and even biocompatible sensor with the same ultrahigh temperature sensitivity. Such a sensor could be moulded into arbitrary shapes and produced at extremely low cost. This will open the door to new applications for thermal sensors in biomedical devices, consumer products and low cost thermal cameras.
INFORMATION:
Literature reference
Di Giacomo R, Daraio C, Maresca B: Plant nanobionic materials with a giant temperature response mediated by pectin-Ca2+. PNAS 2015, doi: 10.1073/pnas.1421020112
Scientists have found a way to measure the unseen toll that environmental stress places on living creatures -- showing that they can rev up their metabolism to work more than twice as hard as normal to cope with change.
Stresses from climate change such as rising temperatures and increasing ocean acidity can edge an organism closer and closer to the brink of death without visible signs. In fact, the researchers -- led by USC's Donal Manahan -- were surprised at just how good organisms can be at hiding the stress they're under.
Manahan and his colleagues found that increasing ...
A study of peanut consumption showed that including them as a part of a high fat meal improved the post-meal triglyceride response and preserved endothelial function.
"Peanuts are a healthy snack when eaten as part of a healthy diet," said lead researcher Xiaoran Liu, a graduate student in the Department of Nutritional Sciences at The Pennsylvania State University.
The purpose of this research was to evaluate vascular function after a high fat meal challenge. Overweight males (n = 15) were randomized to either a peanut meal containing 3 oz. of ground peanuts (as ...
CORVALLIS, Ore. - A new analysis reported in JAMA Psychiatry raises serious questions about the increasingly common use of second-generation antidepressant drugs to treat anxiety disorders.
It concludes that studies supporting the value of these medications for that purpose have been distorted by publication bias, outcome reporting bias and "spin." Even though they may still play a role in treating these disorders, the effectiveness of the drugs has been overestimated.
In some cases the medications, which are among the most widely prescribed drugs in the world, are ...
MADISON - Research has discovered a role for prolactin, the hormone that stimulates milk production in nursing mothers, in the bond between parents.
The study relied on hormone analyses of urine from cotton-top tamarins, a small, endangered monkey native to Colombia. They live in monogamous family groups where both parents help care for the young, which is similar to humans.
The study found a link between prolactin levels and sexual activity and cuddling among paired adults. Although this was a first for prolactin, it has previously been found for oxytocin, a hormone ...
The decades worth of data that has been collected about the billions of neurons in the brain is astounding. To help scientists make sense of this "brain big data," researchers at Carnegie Mellon University have used data mining to create http://www.neuroelectro.org, a publicly available website that acts like Wikipedia, indexing physiological information about neurons.
The site will help to accelerate the advance of neuroscience research by providing a centralized resource for collecting and comparing data on neuronal function. A description of the data available and ...
MADISON - Even during a good year, soybean farmers nationwide are, in essence, taking a loss. That's because changes in weather patterns have been eating into their profits and taking quite a bite: $11 billion over the past 20 years.
This massive loss has been hidden, in effect, by the impressive annual growth seen in soybean yields thanks to other factors. But that growth could have been 30 percent higher if weather variations resulting from climate change had not occurred, according to a study by University of Wisconsin-Madison agronomists published last month in Nature ...
BOSTON -A study led by Boston Medical Center (BMC) researchers demonstrates that while new therapies to treat Hepatitis C Virus (HCV) are highly effective, they are cost-effective and provide the greatest value in specific groups of HCV-infected patients. The findings of the study, led by Benjamin P. Linas, MD, MPH, from BMC's section of infectious diseases and the Boston University School of Medicine (BUSM), are published in the Annals of Internal Medicine.
The study focused on the combination of sofosbuvir and ribavirin for treatment of HCV genotypes 2 and 3, which ...
CLEVELAND - Adding to the clinical benefits and improved patient outcomes associated with minimally invasive surgery, Medtronic highlighted a study published in the March 25 online edition of JAMA Surgery. The new study demonstrated that patients who underwent laparoscopic colectomy procedures required fewer days of health care utilization and the health care system spent less on their acute and follow-up care than those who underwent traditional open surgery.
"We found that the use of minimally invasive laparoscopic approaches in a select group of patients undergoing ...
(Boston, MA) March 30, 2015 - A new study presented today at Experimental Biology 2015 confirms that vegetable consumption is very low among women of childbearing age (WCBA), and that the nutrient-rich white potato is an important vegetable to this population's diet, particularly among subgroups with the lowest intake.
The results are consistent with the Institute of Medicine findings that mean total vegetable consumption of women ages 19 to 50 years is extremely low--with intakes at just 50% of the 2.5 cup equivalents per day recommended for most WCBA by the 2010 Dietary ...
WASHINGTON D.C., March 30, 2015 - Plants living in arid, mountainous and humid regions of the planet often rely on their leaves to obtain the moisture they need for survival by pulling mist out of the air. But how exactly they manage this feat has been a bit of a mystery--until now.
By studying the morphology and physiology of plants with tiny conical "hairs" or microfibers on the surface of their leaves, such as tomatoes, balsam pears and the flowers Berkheya purpea and Lychnis sieboldii, a team of researchers in Japan uncovered water collection-and-release secrets that ...
