A Review on Microfluidics-Based Impedance Biosensors.

Electrical impedance biosensors are powerful and continuously being developed for various biological sensing applications. In this line, the sensitivity of impedance biosensors embedded with microfluidic technologies, such as sheath flow focusing, dielectrophoretic focusing, and interdigitated electrode arrays, can still be greatly improved. In particular, reagent consumption reduction and analysis time-shortening features can highly increase the analytical capabilities of such biosensors. Moreover, the reliability and efficiency of analyses are benefited by microfluidics-enabled automation. Through the use of mature microfluidic technology, complicated biological processes can be shrunk and integrated into a single microfluidic system (e.g., lab-on-a-chip or micro-total analysis systems). By incorporating electrical impedance biosensors, hand-held and bench-top microfluidic systems can be easily developed and operated by personnel without professional training. Furthermore, the impedance spectrum provides broad information regarding cell size, membrane capacitance, cytoplasmic conductivity, and cytoplasmic permittivity without the need for fluorescent labeling, magnetic modifications, or other cellular treatments. In this review article, a comprehensive summary of microfluidics-based impedance biosensors is presented. The structure of this article is based on the different substrate material categorizations. Moreover, the development trend of microfluidics-based impedance biosensors is discussed, along with difficulties and challenges that may be encountered in the future.

Cancer immunotherapy µ-environment LabChip: taking advantage of optoelectronic tweezers.

A cancer immunotherapy µ-environment LabChip, equipped with titanium oxide phthalocyanine (TiOPc)-based optoelectronic tweezers (OET) to achieve direct cell-cell contact, can be used to study the interaction between immune cells and other cells for real-time analysis of NK cells' behavior. In microfluidic devices, it is difficult to solve dead zone problems and observe dynamic cell-cell interactions. We have created a stable and static culture µ-environment which can enhance NK cell activities. In addition, OET is used to solve dead zone problems by manipulating a single cell into four-leaf-clover-shaped (FLCS) microwells made of poly(ethylene glycol) diacrylate (PEG-DA) through optofluidic maskless lithography, causing direct cell-cell contact. Our design reconstructed an in vitro human immune system for the study of dynamic immunological response. When the NK cells came into contact with the target cells in the µ-environment LabChip, we observed that the target cells showed apoptotic characteristics (i.e. cell shrinkage and blebbing within 2 h and then die within 3 h). In addition, our µ-environment LabChip demonstrated higher NK cell activity compared with conventional analysis. We have created an innovative cancer immunotherapy µ-environment LabChip to provide a stable and static µ-environment for cell-cell interaction study. Furthermore, our µ-environment LabChip showed the potential to enhance NK cell activity and to study immunological interactions between immune cells and cancer cells dynamically.

A novel dynamic sensing of wearable digital textile sensor with body motion analysis.

This work proposes an innovative textile sensor system to monitor dynamic body movement and human posture by attaching wearable digital sensors to analyze body motion. The proposed system can display and analyze signals when individuals are walking, running, veering around, walking up and down stairs, as well as falling down with a wearable monitoring system, which reacts to the coordination between the body and feet. Several digital sensor designs are embedded in clothing and wear apparel. Any pressure point can determine which activity is underway. Importantly, wearable digital sensors and a wearable monitoring system allow adaptive, real-time postures, real time velocity, acceleration, non-invasive, transmission healthcare, and point of care (POC) for home and non-clinical environments.