Experiment MIKROVIB


Tremor phenomena are the micro-vibrations of spontaneous trembling appearing all over the body of endotherms – It disturbs, for example by passing a thread through the eye of a needle. Even though it is weak, it is detectable with every movement and even during resting. The loss of gravity effects a reorganization of sensorium and locomotor system in the longterm. Studies have shown that tremors can increase after a space flight.

Objectives

In many diseases, like for example, Parkinson’s and the intake of pharmaceuticals, more strong changes in the tremor’s appearance take place. The measuring of these negligible trembles can determine the physical and psychological stress of the body. Tremors play an important role in man-machine systems where man himself controls functions of an intelligent controller, for example, control of devices.

Microgravity offers the possibility to investigate this phenomen. The muscles back-up motor activity demand less and the musculature changes in general. Better conclusions can be drawn when comparing these micro vibrations with experiments on earth. Measurements were taken using exactly defined strain and after intensive training. This happened six times before the flight, two times during the flight and multiple times after the flight.

For the purpose of the PULSTRANS and MIKROVIB experiments, a KYMO apparatus was developed. The apparatus consisted of a sensor vest, data-entry and recording, and an ergometer.

Functionality, Measuring principle

The function of the arms, hands and fingers are especially important for fine-motor abilities. As such, the investigations were carried out on the right forearm of the Austrian cosmonaut. The tremors were recorded using a sensitive acceleration measurement device on the elbow and arm joint. Strain measurements were recorded using a special hand ergometer, measuring static as well as dynamic strength (approximately the hand’s strength tremor). An accompanying ECG uniquely showed which influences the heart beart has on the micro vibrations.

Special sensors were developed in order to measure these activities. These sensors had to meet the various demands, so they had to be highly sensitive and less interference-prone. One expected that they did not interfere with the cosmonaut and at the same time be highly flexible but with tearproof cable connections. They had to be small and weigh as little as possible. In order to meet all these requirements, a sensor vest made from merino wool was developed. The fasteners were made from apple wood. This vest was used in the PULSTRANS and MIKROVIB experiements.

Shared equipments of the Austrian payload

DATAMIR, KYMO

Results

Such typical vibrations on board the MIR space station have a frequency of eight to twelve Hertz. These are known as neutral tremors of micro vibrations and were not registered (experiment part NEUTRAL 1/1). One knows that tremors monitored on earth do not exclusively lead to mechanical factors. Therefore an explanation model for the development of these neutral tremors has to be found. The activity of the back-up motor apparatus must play an important role in this model. A tremor resulted in the arm position “arm stretched to the front” (NEUTRAL 1/2), but was greatly reduced compared with the terrestrial reference investigations. This is due to the elastic deformation and extension status of the muscles. An increase of the tremors (tone) was also observed in the muscles, even though they are not part of the arm musculature, but are relevant for the arm position being investigated. A distinctive peek of four to five Hertz was registered under microgravity conditions during the NEUTRAL 1 test. This could not be observed in terrestrial investigations. It was presumed that these vibrations result from changes of the outgoing influences of the cerebellum’s lateral segment.

No changes in the strength tremors when maintaining the strength level with various amplitudes (ERGO 2) were observed. A strong anomaly resulted when maintaining 60% of the strength level during the flight’s second investigation. This could be a rash weariness under microgravity conditions. Test ERGO 1 investigated the appearance of tremors during the excercising of various controlling activities. A tendential error increase appeared in sinusoidal strength tracing. However, the cosmonaut had no problems in accomplishing all tasks.

The results of the wave dispertion confirm the effectivity of the methods used. The observed increase of the transfer properties during the flight showed an increase of the viscous components in the tissues, that is, a decrease in stiffness. The causes are suspected to be in the fluid movement between the upper and lower body parts rather than in changes of the musculature. The experience learned from the experiment should serve as a further improvement of monitoring methods: Planned is a drecrease of the gap between sensors, a reduction of the sensors themselves as well as the placement of sensors and vibro-stimulators within one casing.

The MIKROVIB experiment showed for the very first time the possibility to quantitavely evaluate the changes of various tremor parameters.

Practical application
Application ranges
  • Physiological investigation of the tremor and the motor system at stress
  • Physiology and pathophysiology
  • Diagnostics and care checkup at patients with various neurological pathologies
  • Occupational medicine
Application target
  • Checkup the formation mechanism of the micro-vibration and the physiological tremor
  • Monitoring psycho-physiological parameter at stress
  • Diagnostics neurological troubles
  • Checkup of the therapy and rehabilitation measures
  • Test and monitoring of the functional and psycho-physiological state of persons with various occupational
Direct interested institutions on the utilization of the experiment results
  • Physiological Institute, University Graz
  • Institute for Elektro- and Biomedical Technics, Technical University Graz
  • Institute for Biomedical Problems, Moscow
  • University Clinic for Psychiatry, Graz
  • University Clinic for Neurology, Innsbruck
  • Institute for Neurology RAMN, Moscow
  • Center for Cerebral Palsy, Moscow
  • Institute for Sport Medicine, Vienna
Technical characteristics

The equipment MIKROVIB consisted of the following units

Electrical principle circuit diagram of the project MIKROVIB. Chart: BMBWK, Vienna
Equipment KYMO with the electronic box KYMO (left) and the sensor vest KYMO (right). Photo: Univ.-Prof. Dr. Maximilian Moser, Graz
Aluminium container with foam coating
  • Equipment KYMO
  • Cable KYM1 (power supply)
  • Cable KYM2 (connection KYMO – DATAMIR)
  • Sensor vest with
    Vibrostimulator
    Accelerometer (2 pieces)
    Puls sensores (3 pieces)
    ECG – cable
    Pre-amplifier unit
  • Hand ergometer
  • Accessory sets for the experiment MIKROVIB (2 pieces)
    Adherance rings (3 pieces), Adherance discs (6 pieces)
    Cleaning tissues (2 pieces), ECG – Electrodes (3 pieces)
  • Accessory sets for the experiment PULSTRANS (2 pieces)
    Adherance rings (3 pieces), Adherance discs (6 pieces)
    Cleaning tissues (2 pieces), ECG – Electrodes (3 pieces)
  • Accessory sets for the experiment SLEEP (2 pieces)
    Adherance rings (3 pieces), Adherance discs (6 pieces)
    Cleaning tissues (2 pieces), ECG – Electrodes (3 pieces)
  • Fixing devices for the puls sensors (3 pieces)
  • Adhesive tapes to fix the vibrostimulator and
    accelerometer on the skin of the subject
  • Jig for the standardised fixation of vibrostimulator and
    accelerometer on the skin of the subject
  • Reserve fuses
Mass:max. 6,2 kg
Dimensions:350 mm x 350 mm x 140 mm
Power input:max. 35 W
Experimenters

o. Univ.-Prof. Dr. Thomas Kenner (institute manager)
Dipl.-Ing. Dr. Eugen Gallasch (project manager)
Univ.-Doz. Dr. Maximillian Moser
Josef Hindinger
Herbert Eder
Bernhard Wronski
Kurt Maass
Kurt Ansperger
Dipl.-Ing. Dr. Gerhard Wiesspeiner
Univ.-Prof. Dr. Gerhard Pfurtscheller
all: Physiological Institute of the University Graz