Molecular acoustics
The molecular acoustics is the study of the mechanism of transmission of sonic energy by molecules in fluids and gases. She is particularly concerned with the relationship between ultrasound and molecular structure , i.e. the question of how the sound energy is transmitted from molecule to molecule in a sound field .
Theoretical foundations
The most important parameters for describing such a sound field are the speed of sound and sound absorption . The speed of sound of a substance is higher, the higher its density . Therefore, conclusions can be drawn from the speed of sound about the density properties of the sonicated material. Far-reaching experiments that led to this finding and ultimately to the relevant reference values , go back to Werner Schaaffs , who presented the standard work in this area that is still valid today with an extensive collection of tables and the corresponding theoretical treatise.
The first research in the field of acoustics and in the field of molecular acoustics are historically inseparable from each other. Only the rapidly developing relevant technology from the beginning to the middle of the 20th century made it increasingly possible to investigate even the smallest chemical units (atoms) and their compounds (molecules). As in many areas of scientific research, this also applies to molecular acoustics, which has been increasingly considered separately since then.
history
Molecular acoustics could be clearly distinguished from the research field of known acoustics for the first time with the development of the first ultrasonic interferometer for measuring the speed of sound in gases by George W. Pierce in 1925. The further development of this apparatus by Hubbard and Loomis in 1927 then also led to the measurement of the Speed of sound of liquids through biquard. One of the first acoustics experts to deal with this topic in German-speaking countries was the physicist Erwin Meyer , who had made it scientifically known in the field of acoustics in the 1930s. In the article “The importance of acoustics in the context of physics and technology”, published in 1936 at the 12th German Physics and Mathematicians' Day together with his doctoral supervisor Erich Waetzmann , the authors considered a. the role of ultrasonic spectroscopy in molecular acoustics. Erwin Meyer continued to work on ultrasound research during and after the Second World War.
The methods he used to measure the speed and attenuation of sound in liquids gained wide scientific recognition through the Nobel Prize awarded by Manfred Eigen, who taught with him at the University of Göttingen in 1967. He had measured the speed of chemical reactions in aqueous solutions and wanted to find out which ones Intermediate products would arise. The easiest way to do this, according to his hypothesis, is to first establish an equilibrium and then disturb it in order to be able to measure the time until it is restored. To do this, he initially used ultrasound, with which he could generate tiny changes in pressure in his artificially created equilibrium and measure reaction speeds of up to about a microsecond.
In the second half of the 20th century, research in the field of molecular acoustics declined in favor of the emerging laser spectrography. The reasons for this were the requirements for evaluating the enormous volumes of data that computers did not meet until around the turn of the millennium, as well as the fact that electromagnetic spectra are easier to separate than acoustic ones, which greatly simplifies their analysis.
Current application and further potential
Imaging acoustic methods for diagnostic purposes are mainly known today in medicine, referred to here as sonography (e.g. in the context of prenatal care). In contrast, non-imaging ultrasound diagnostics is only used in industry in a few specialized areas, for example in materials science (see ultrasound testing ) and in sensors for measuring the quality of liquids such as machine oil.
In principle, a number of areas are conceivable in which this technology could open up new areas of application.
On the one hand, this includes the classification of liquids, chemicals and tissues. In laboratory diagnostics, substances such as blood and enzymes can be tested quickly and easily for previously sampled indications using molecular acoustic methods. Investment-intensive goods such as medicines or luxury products as well as sensitive materials such as body tissue can also be checked for authenticity or quality without damage.
In addition, medicine offers a broad field of research in the acute and permanent monitoring of brain tissue for various diagnoses: this includes the detection of lesions in the white tissue in patients with atrial fibrillation, who are suspected of causing dementia. The identification of stroke risk groups could also be proven with the help of molecular acoustic methods.
literature
- Surface tension and speed of sound R. Experientia, 1948, Volume 4, Issue 12
- Molecular & Quantum Acoustics , trade journal
Individual evidence
- ↑ Schaaffs: Molecular Acoustics - An Introduction to the Relationship between Ultrasound and Molecular Structure in Liquids and Gases 1963
- ↑ Hellwege (ed.), Schaaffs (author): Landolt-Börnstein (volume) - Numerical Data and Functional Relationships in Science and Technology, Molecular Acoustics, Volume 5, 1967
- ^ Matheson: Molecular Acoustics, 1971
- ^ Hubbard & Loomis: A Sonic Interferometer for Liquids 1927
- ^ Matheson: Molecular Acoustics, 1971
- ↑ Guicking Erwin Meyer - an important German acoustician; Biographical Notes 2012
- ↑ Universal Lexicon: Nobel Prize in Chemistry 1967 2015
- ↑ DEGUM: Baby ultrasound in pregnancy 2012
- ↑ US Patent 7043969 , 2006
- ↑ US Patent 6873916 , 2005
- ↑ Fraunhofer IZI: Ultrasound Broadband Spectroscopy System ( Memento of the original from August 11, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Last accessed: August 11, 2016
- ↑ Olszewski et al: The novel non-invasive ultrasound device for detecting early changes of the brain in patients with heart failure, European Journal of Heart Failure 2016, Volume 18, Issue 5
- ↑ Dobkowska-Chudon et al: Utilizing Comparison Magnetic Resonance Imaging and Acoustocerebrography Signals in the Assessment of Focal Cerebral Microangiopathic Lesions in Patients with Asymptomatic Atrial Fibrillation (Preliminary Clinical Study Results), Archives of Acoustics 2016, Volume 41, Issue 2
- ↑ UHN Toronto: The Aging Brain 2014, last accessed August 15, 2016
- ↑ Wrobel et al: On ultrasound classification of stroke risk factors from randomly chosen respondents using non-invasive multispectral ultrasonic brain measurements and adaptive profiles , Biocybernetics and Biomedical Engineering 2015, Volume 35, Issue 4
