Simultaneous detection of the shuttling motion of liquid metal droplets in channels under alternating pressure and capacitive sensor signals

Implementing a signal-switching mechanism for the selective use of integrated sensors and actuators plays a crucial role in streamlining the functionality of miniaturized devices.Here,a liquid metal droplet(LMD)-based signal-switching mechanism is introduced to achieve such functionality.Pressure modulation with a 100-μm spatial resolution enabled precise control of the position of the LMDs within a channel.After integrating the channel with asymmetrically structured electrodes,the effect of the shuttle-like movement of LMD on the temporal changes in the overall capacitance was investigated.Consequently,analysis of the capacitive peaks revealed the directional movement of the LMDs,enabling estimation of the position of the LMDs without direct observation.In addition,we achieved successful signal extraction from the capacitive sensor that was linked to the activated electrodes,thereby enabling selective data retrieval.The proposed signal-switching mechanism method achieved a detection accuracy of~0.1 pF.The sensor’s ability to simultaneously detect the LMD position and generate a signal underscores its significant potential for multiplexing in multisensing systems,particularly in concealed environments,such as in vivo settings.

Implementation of soft microfingers for a hMSC aggregate manipulation system

This paper describes a pneumatic balloon actuator(PBA)composed of polydimethylsiloxane(PDMS)for cellular aggregate manipulation.We evaluated the ability of the microdevice to manipulate a tiny and sensitive cellular aggregate without causing serious damage.We used human mesenchymal stem cells(hMSCs)for the cellular aggregate.We describe the design,fabrication,characterization and operation of the soft microfingers to pinch and release a spherical hMSC aggregate(φ200μm),and we employed a PBA to serve as an artificial muscle to drive the microfingers.A design of the microfingers in terms of dimensions,generated force and contact conditions was accomplished.The designed dimensions of a single finger were 560μm×900μm.In summary,we demonstrate the utility of the surface modification of a fingertip for pinching and releasing a cellular aggregate and describe a manipulation system that was constructed to drive and control the microfingers.The implemented manipulation system,which is composed of microfingers and a positioning mechanism,was tested and verified in a series of operations.

An openable artificial intestinal tract system for the in vitro evaluation of medicines

In vitro drug screening systems for pharmacological targets have been studied as substitutes for whole-animal experiments.Cultured cells or tissues provide promising substitution models when coupled with technological innovations in micro total analysis systems.In this study,we focus on an intestinal drug absorption assay,as the oral route is most frequently used for drug administration.Pharmacological studies have reported the development of artificial vessels that include tubular structures.However,it is difficult to observe the insides of these tubes in situ.To address this problem,we developed a micro-device that uses a pneumatic balloon actuator(PBA)to open and close an artificial intestinal tract.A human colon carcinoma cell line(Caco-2)was cultivated on the flat surface of the micro-device for 7 days to form the inner cellular layer of an artificial intestinal tract with which to evaluate drug transport.The artificial intestinal tract was completely actuated from a flat plate to a circular tube via a PBA with a pressure of 65 kPa,and drugs were perfused at a flow rate of 0.05 mL min^(−1) into the tubular artificial intestinal tract for 1 h.Using the openable artificial intestinal tract,the in vitro absorption of calcein and Texas Red were successfully estimated as models of hydrophilic and hydrophobic drugs,respectively.The artificial intestinal tract enables the effective evaluation of the in vitro intestinal absorption of drug candidates and contributes to the reduction of costs incurred during the initial stage of drug development.