ABSTRACT
Aims: Design and assembly of an inexpensive microfluidic PDMS chip for visual detection of cell adhesion and biofilm formation. Study Design: Three different styles of microchannels (2.6, 5.0, and 11.5 µl volumes) were designed, fabricated and tested for adhesion and biofilm formation in a microfluidic system. The pressure drop measurements system includes a bio-Ferrograph connected to the PDMS microchannel via a syringe and a pressure transducer. Methodology: Microfluidic chips were fabricated using Polydimethylsiloxane (PDMS) by means of soft lithography. Different cell densities of E.coli K12 cells were introduced to investigate adhesion and biofilm formation at different time intervals. Stabilization time and hydraulic resistance were obtained via a Bio-Ferrograph connected to a pressure transducer. Results: PDMS microfluidic volume (2.6 µl) failed to generate noticeable biofilm, while slight and greatest yield occurred with PDMS microchannels (5.0, and 11.5 µl), respectively, and could detect as low as 26 cells in 11.5 µl microchannel. As incubation time and/or initial cell density increases, cell adhesion increased, illustrated by crystal violet color intensity. High stabilization time (3 h) didn’t allow for bacterial attachment and cultivation inside the microchannel (2.6 µl) while lower stabilization time (10 min) yielded the highest capacity of cell adhesion in microchannel (11.5 µl). Conclusions: We developed a microfluidic chip with low stabilization time and hydraulic resistance, thus offering more volume for adhesion of bacterial cells and biofilm formation. It allowed bacterial cultivation without any addition of nutrients. The microfluidic chip provides a platform to monitor biofilm growth and can be integrated in situ investigations for biological systems, food biotechnology and other industrial biotechnology applications. This would allow a non-destructive and non-invasive monitoring of the biofilm-forming bacteria inside the PDMS microfluidic chip. This work opens opportunities for further investigations of pressure drop phenomena in microchannels that would otherwise go unnoticed in macro scale measurements.
ABSTRACT
Qi, blood and the meridians are fundamental concepts in Chinese medicine (CM), which are components of the human body and maintain physiological function. Pathological changes of qi, blood and meridians may lead to discomfort and disease. Treatment with acupuncture or herbal medicine aims to regulate qi and blood so as to recover normal function of the meridians. This paper explores the nature of qi as well as compares and correlates them with the structures of the human body. We propose a conceptualization of qi as being similar to the interstitial fluid, and the meridians as being similar to interstitial space of low hydraulic resistance in the body. Hence, qi running in the meridians can be understood as interstitial fluid flowing via interstitial space of low hydraulic resistance.
Subject(s)
Humans , Acupuncture Points , Connective Tissue , Physiology , Extracellular Fluid , Physiology , Extracellular Space , Physiology , Meridians , Qi , WaterABSTRACT
Objective To measure the interstitial fluid pressure (IFP) on low hydraulic resistance channel along meridians and observe the difference and fluctuation. Method Low hydraulic resistance points (LHRP) and non LHRP were measured on anesthetized mini pigs by a scanning hydraulic resistance measuring device. The IFP was then measured by wick in needle method on these two regions. Results The stomach meridian, kidney meridian and conceptual vessel meridian on mini pigs were measured. The IFP were significantly lower than non LHRP region on the above three meridians(P<0.05), the differences of which were 1.06，0.70，3.69 mmHg respectively with the total pressure difference of 1.44 mmHg and pressure gradient of 1.44~2.88 mmHg/cm（1 mmHg=0．133 kPa）. Conclusions Among the peripheral subcutaneous tissues, there exists a difference of IFP toward the meridian which may drive the flow of interstitial fluid toward the meridians.