科学家研发石墨烯材料传感器可检测分子级气体浓度变化

英国南安普顿大学和日本先进科学技术研究所的科学家研发了一种以石墨烯为原材料的传感器,能检测出室内空气污染且精度极高。这一研究近日发表在《科学进展》期刊上。

新研发的传感器可以感应到来自建筑、家具用品的二氧化碳分子以及挥发性有机化合物(VOC)气体分子。

近年来,由个人居住环境中的空气污染引起的健康问题与日俱增。这些有害化学气体的浓度水平一般在几十亿分之一(ppb),用现有的环境传感技术难以检测到,因为这些传感器只能检测到浓度为百万分之一(ppb)的此类气体。

该研究团队研发出的石墨烯传感器在通电后,可使单个的二氧化碳分子一个一个吸附到石墨烯材料上,并在分子水平上检测其浓度。其具体方法是,通过监测石墨烯材料的电阻值,石墨烯材料对二氧化碳分子的吸附和释放会以电阻“量子化”波动的形式被检测到。在实验中,研究人员只花费了几分钟就检测到浓度约为30ppb的二氧化碳气体。 来源:科技日报

Graphene-based sensor detects harmful air pollution in the home

A diagram of a graphene single molecular sensor (left) and the observed signal showing successful detection of single CO2 molecule adsorption / desorption events. Credit: University of Southampton
Scientists from the University of Southampton, in partnership with the Japan Advanced Institute of Science and Technology (JAIST), have developed a graphene-based sensor and switch that can detect harmful air pollution in the home with very low power consumption.

The sensor detects individual CO2 molecules and volatile organic compound (VOC) gas molecules found in building and interior materials, furniture and even household goods, which adversely affect our living in modern houses with good insulation.

These harmful chemical gases have low concentrations of ppb (parts per billion) levels and are extremely difficult to detect with current environmental sensor technology, which can only detect concentrations of parts per million (ppm).

In recent years, there has been an increase in health problems due to air pollution in personal living spaces, known as (SBS), along with other conditions such as sick car and sick school syndromes.

The research group, led by Professor Hiroshi Mizuta, who holds a joint appointment at the University of Southampton and JAIST, and Dr Jian Sun and Assistant Professor Manoharan Muruganathan of JAIST, developed the sensor to detect individual CO2 molecules adsorbed (the bond of molecules from a gas to a surface) onto the suspended (single atomic sheet of carbon atoms arranged in a honeycomb-like hexagonal crystal lattice structure) one by one by applying an electric field across the structure.

By monitoring the electrical resistance of the graphene beam, the adsorption and desorption (whereby a substance is released from or through a surface) processes of individual CO2 molecules onto the graphene were detected as ‘quantised’ changes in resistance (step-wise increase or decrease in resistance). In the study, published today in Science Advances, the journal of the American Association for the Advancement of Science (AAAS), a small volume of CO2 gas (equivalent to a concentration of approximately 30 ppb) was released and the detection time was only a few minutes.

Professor Mizuta said: “In contrast to the commercially available environmental monitoring tools, this extreme sensing technology enables us to realise significant miniaturisation, resulting in weight and cost reduction in addition to the remarkable improvement in the detection limit from the ppm levels to the ppb levels.”

Research group members, Dr Harold Chong from Southampton and Dr Marek Schmidt and Dr Jian Sun of JAIST, have also recently developed graphene-based switches (published in the March issue of Nanoscale, the journal of the Royal Society of Chemistry) using a uniquely thin film developed at the University of Southampton.

The switches, which require remarkably low voltages (below three volts), can be used to power electronic components on demand, greatly improving the battery lifetime of personal electronic devices.

Professor Mizuta and the research group are now aiming to bring the two technologies together to create ultra-low-power environmental sensor systems that can detect single .

Explore further: Novel technique used to study graphene’s response to air

More information: Room temperature detection of individual molecular physisorption using suspended bilayer graphene, Science Advances, DOI: 10.1126/sciadv.1501518