| 摘要: | 儘管人體在靜態平躺時，不同尺度的振動以非線性耦合的方式依舊存在。我們提出用非接觸式的光學顯微鏡來直接觀看人體前手臂的皮膚位移，寬廣的時間及空間解析度方便我們了解以下三個議題: (1)基本人體皮膚之振動模態 (2)判定相關的振動源，融合中西醫觀點，潛在振動源如呼吸、心跳、脈搏、震顫還有穴位振動皆受驗證 (3) 振動模態的耦合。前手臂被分成遠離動脈區的振動和動脈區的振動，遠離動脈區的振動模態可從頻譜分析分成低頻帶、中頻帶、高頻帶，各頻帶的主要信號分別是源自由呼吸引發的0.2赫茲、由心跳引發的1赫茲和其諧波至大約8赫茲、一個中心大約在10赫茲小丘狀的寬頻，經過帶通濾波後可看出中頻和高頻的信號彼此相位鎖定可認定兩者皆由心臟跳動產生的振動。用particle image velocimetry (PIV) 檢視空間振動模態發現整體近乎一致，簡稱為全域振動，穴道及經絡並未產生振動的奇異點或通道。在動脈區的振動透過PIV找出週期性收縮的奇異點，得出此區的振動是由前述的全域振動和動脈引發的區域振動所合成，分析動脈振動的頻譜發現，相較全域振動，只存在中頻帶的由脈膊引發的1赫茲和其諧波，並且頻率皆和全域振動一致。其時域圖中則可看出和呼吸週期一致的振幅調制。;Human body is an interesting complex network exhibiting multi-scales of nonlinearly coupled mechanical vibrations, even for a resting subject. For example, respiration, heartbeat, muscle tremor, and local artery pulsation are the possible sources inducing global or local mechanical vibrations.
In this work, skin vibrations of the different regions on the forearms of resting subjects, are explored, using a simple noncontact method, direct visualizing skin displacement through optical video microscopy by digital tracking skin tracer motions. The measurement provides a good bandwidth up to a few tens of Hz, and spatial resolution down to 1 um. The skin velocity field in the viewing plane can also be obtained from sequential images through particle image velocimetry (PIV). By comparing the vibrations of a pair of separated regions from two synchronized video-microscopes, the following interesting issues are addressed: (i) What are the generic behaviors and differences of skin vibrations of different regions, especially around radial artery, acupuncture points along the lung meridian and sham points? (ii) Are acupuncture points the singular points for skin vibrations? (iii) What are the origins for those skin vibrations, and how are different modes correlated?
It is found that, except the radial artery region, all other tested regions in forearms show similar vibration waveforms, originated from the global mechanical vibration induced by heartbeat and respiration in the trunk, regardless of whether there are nearby meridians. The global vibration contains a low-frequency respiratory mode around 0.2 Hz, and a middle-frequency band with distinguished fundamental heartbeat around 1 Hz and its few higher order harmonics, on a floor following power law decay. Moreover, a wide band bump centered around 10 Hz with a few Hz band width, out of the power law decay spectrum floor is observed. The band pass filtered 10 Hz high-frequency waveform is modulated by the heartbeat. The above observations suggest that heartbeat and respiration are the two major sources of trunk vibration and consequently global vibrations in upper limbs. Around the radial artery, superposed on the global vibration, arterial pulses induce additional local vibration. It only contains the middle-frequency modes from about 1 Hz to its harmonics up to a few Hz, excluding low frequency respiration and the 10 Hz high-frequency modes. The middle-frequency vibration induced by artery is phase-locked and frequency-locked with the middle-frequency global vibration, and is modulated by the slow respiration mode. |
