electroantennography-based-bio-hybrid-odor-detecting-drone-using

Electroantennography-based Bio-hybrid Odor-detecting Drone using Silkmoth Antennae for Odor Source Localization

Small drones with chemical or biosensor devices that can detect airborne odorant molecules have attracted considerable attention owing to their ...

The University of Tokyo

the university of tokyo

Field-effect transistor (FET)-based biosensors have a wide range of applications, and a bio-FET odorant sensor, based on insect (Sf21) cells expressing insect odorant receptors (ORs) with sensitivity and selectivity, has emerged. To fully realize the practical application of bio-FET odorant sensors, knowledge of the cell-device interface for efficient signal transfer, and a reliable and low-cost measurement system using the commercial complementary metal-oxide semiconductor (CMOS) foundry process, will be indispensable. However, the interfaces between Sf21 cells and sensor devices are largely unknown, and electrode materials used in the commercial CMOS foundry process are generally limited to aluminium, which is reportedly toxic to cells. In this study, we investigated Sf21 cell-device interfaces by developing cross-sectional specimens. Calcium imaging of Sf21 cells expressing insect ORs was used to verify the functions of Sf21 cells as odorant sensor elements on the electrode materials. We found that the cell-device interface was approximately 10 nm wide on average, suggesting that the adhesion mechanism of Sf21 cells may differ from that of other cells. These results will help to construct accurate signal detection from expressed insect ORs using FETs.

Increasing cell-device adherence using cultured insect cells for receptor-based biosensors.

The advent of 3D-printing technologies has had a significant effect on the development of medical and biological devices. Perfusion chambers are widely used for live-cell imaging in cell biology research; however, air-bubble invasion is a pervasive problem in perfusion systems. Although 3D printing allows the rapid fabrication of millifluidic and microfluidic devices with high resolution, little has been reported on 3D-printed fluidic devices with bubble trapping systems. Herein, we present a 3D-printed millifluidic cartridge system with bent and flat tapered flow channels for preventing air-bubble invasion, irrespective of bubble volume and without the need for additional bubble-removing devices. This system realizes bubble-free perfusion with a user-friendly interface and no-time-penalty manufacturing processes. We demonstrated the bubble removal capability of the cartridge by continually introducing air bubbles with different volumes during the calcium imaging of Sf21 cells expressing insect odorant receptors. Calcium imaging was conducted using a low-magnification objective lens to show the versatility of the cartridge for wide-area observation. We verified that the cartridge could be used as a chemical reaction chamber by conducting protein staining experiments. Our cartridge system is advantageous for a wide range of cell-based bioassays and bioanalytical studies, and can be easily integrated into portable biosensors.

3D-Printed Bubble-Free Perfusion Cartridge System for Live-Cell Imaging.

The detection of volatile organic compound (VOC) mixtures is crucial in the medical and security fields. Receptor-based odorant biosensors sensitively and selectively detect odorant molecules in a solution; however, odorant molecules generally exist as VOCs in the air and exhibit poor water solubility. Therefore, techniques that enable the dissolution of poorly water-soluble VOCs using portable systems are essential for practical biosensors' applications. We previously proposed a VOC dissolution method based on water atomization to increase the surface area via the generation of fine bubbles, as a proof-of-concept; however, the system was lab-based (non-mobile) and the dissolution was limited to one VOC. In this study, we established a highly effective VOC dissolution method based on mist atomization that can be used in the field. This new method demonstrated a rapid dissolution potential of a sparsely-soluble VOC mixture with various functional groups in distilled water (DW) within 1 min, without the use of any organic solvents. Calcium imaging revealed that odorant receptor 13a-expressing Sf21 cells (Or13a cells) responded to 1-octen-3-ol in the mixture. Further, we successfully developed a field-deployable prototype vacuum and dissolution system with a simple configuration that efficiently captured and rapidly dissolved airborne 1-octen-3-ol in DW. This study proposes a field-deployable system that is appropriate for solubilizing various airborne odorant molecules and therefore is a practical strategy to use in the context of odorant biosensors.

Daigo Terutsuki

Research Center for Advanced Science and Technology

The University of Tokyo

Electroantennography-based Bio-hybrid Odor-detecting Drone using Silkmoth Antennae for Odor Source Localization