Measurement of the body surface physiologic tremor or “microvibration”

Abstract

Although this study was primarily concerned with instrumentation techniques, preliminary observations indicated that the resting hwnan microvibration contains a large cardiovascular component, probably obscured in previous observations with the electrodynamic velocity sensor.Human microvibrations (MY) are normal or physiologic body surface vibrations of micron amplitude, observed at rest. The microvibration has also been termed the normal or minor tremor. Measurement of such vibrations is of significance in study of Parkinsonism and the Intention Tremor (Wachs& Bushes, 1961), and has been used in experimental psychology to distinguish neurotic, schizophrenic and control Ss (Williams, 1964a). Microvibrations may be described in terms of displacement, or its derivatives as: microdisplacement, microvelocity, and microacceleration. Although early research emphasized this response as being neuromuscular and the source of resting muscle tone, more recent work indicates that the source of MV is at least in part cardiovascular (Brumlik, 1962). A lack of suitable instrumentation has obscured both'the source and the nature of this phenomenon.The term, microvibration, was first applied to the minute vibratory movement of the human body surface by Rohracher in 1946, although he first observed the phenomenon in 1943 (1949, 1962b). Other workers studying MV include Denier (1956Denier ( , 1957, Haider & Lindsley (1964), Heller-Jahnl (1959), Marko (1959), Schrocksnadel et al (1956), Sugano (1957), Sugano &Inanaga (1960), and Williams (1963, I964a, b). Although Rohracher described the phenomenon as a normal physiological function involved in generation of resting muscle tone and body temperature regulation, Sugano & Inanaga (1960) described it as a kind of minor tremor.The results of tremor research are closely related to study of the human microvibration; the same instrumentation can be used to study both. Of particular interest in tremor research is the work of Chase et al (1965), Cooper et al (1957), Halliday & Redfearn (1956). Hamoen (1958). Jasper & Andrews (1938), Lansing (1957, Lindsley (1935), Lippold et al (1959, Marshall &Walsh (1956), andTravis (1929). An additional group of workers has studied the "normal or physiologic tremor," which may be an identical phenomenon. This group includes Brumlik (1962), Bushes et al (1960), Wachs et al (1960), and Wachs& Bushes (196 I (1947, 1948), althoush these workers were not specificaDy concerned with MY or tremor measurements.Without doubt, Rohrac:her is the pioneer in themicl'O,ibration field

Recognition of Low Amplitude Body Vibrations via Inertial Sensors for Wearable Computing

“…Preliminary measurements, presented here, with mobile CE (Customer Electronics) devices, namely MetaWatch Strata and TI SensorTag, showed promising results for detecting microvibrations. These results are consistent and are matching with the findings of Pacela [4] in terms of sensor accuracy and technology as well as measured frequency. However, for future wearable application scenarios, the quality of recognition for microvibrations has to be further evaluated.…”

“…sleep detection, anomaly detection etc.). Most of the results presented in previous research where achieved by using stationary devices (e.g., [2], [4], [9]), and therefore is not applicable to most real world scenarios. The aim of this paper was to prove that microvibrations are measureable with mobile inertial sensors.…”

“…Marko [3] made microvibrations visible by magnifying them 400 times with a microscope. Pacela [4] evaluated five sensor technologies for the measurement of human body surface vibrations. Pacela used besides a non-contacting capacitance sensor a seismic (velocity) sensor, linear-variable-differential transformer sensors and a miniature accelerometer.…”

Isometric thermogenesis at rest and during movement: a neglected variable in energy expenditure and obesity predisposition

“…Furthermore, it was observed that microvibration frequency was decreased in a hot environment, increased in the cold, and that such fine tremor is detectable only in warm‐blooded animals . These observations led Rohracher to describe the phenomenon as a normal physiological function involved in the generation of resting muscle tone and that the chemical ‘reaction‐heat’ resulting from muscle microvibration plays a role in maintaining homeothermy . Three decades later, this notion that invisible muscle vibration helps to maintain body temperature gained further support from the studies of Meigal et al who found that the electromyographic signal increased with cooling prior to visible shivering, leading to the term ‘thermoregulatory muscle tone’ or ‘pre‐shivering muscle tone’, which they demonstrated was influenced by head and body posture .…”

“…Minor tremor or microvibration, the phenomenon that the human body skin surface is constantly vibrating even under conditions of relaxation, underwent considerable characterization in the two decades that followed World War II, in large part due to the pioneering work of Rohracher . What he coined as ‘Mikroschwingung’ (or microvibration) was reported to be ever‐present from birth to shortly after death and in all parts of the body.…”