Light-addressable Potentiometric Sensor (LAPS) Combined with Multi-chamber Structures to Investigate the Metabolic Activity of Cells

Light Addressable Potentiometric Sensors for Biochemical Imaging on Microscale: A Review on Optimization of Imaging Speed and Spatial Resolution

Light addressable potentiometric sensors (LAPS) are a competitive tool for unmarked biochemical imaging, especially imaging on microscale. It is essential to optimize the imaging speed and spatial resolution of LAPS since the imaging targets of LAPS, such as cell, microfluidic channel, etc., require LAPS to image at the micrometer level, and a fast enough imaging speed is a prerequisite for the dynamic process involved in biochemical imaging. In this study, we discuss the improvement of LAPS in terms of imaging speed and spatial resolution. The development of LAPS in imaging speed and spatial resolution is demonstrated by the latest applications of biochemistry monitoring and imaging on the microscale.

The Light-Addressable Potentiometric Sensor and Its Application in Biomedicine towards Chemical and Biological Sensing

The light-addressable potential sensor (LAPS) was invented in 1988 and has developed into a multi-functional platform for chemical and biological sensing in recent decades. Its surface can be flexibly divided into multiple regions or pixels through light addressability, and each of them can be sensed independently. By changing sensing materials and optical systems, the LAPS can measure different ions or molecules, and has been applied to the sensing of various chemical and biological molecules and cells. In this review, we firstly describe the basic principle of LAPS and the general configuration of a LAPS measurement system. Then, we outline the most recent applications of LAPS in chemical sensing, biosensing and cell monitoring. Finally, we enumerate and analyze the development trends of LAPS from the aspects of material and optical improvement, hoping to provide a research and application perspective for chemical sensing, biosensing and imaging technology.

Light-Addressable Potentiometric Sensors in Microfluidics

The light-addressable potentiometric sensor (LAPS) is an electrochemical sensor based on the field-effect principle of semiconductors. It is able to sense the change of Nernst potential on the sensor surface, and the measuring area can be controlled by the illumination of a movable light. Due to the unique light-addressable ability of the LAPS, the chemical imaging system constructed with the LAPS can realize the two-dimensional image distribution detection of chemical/biomass. In this review, the advantages of the LAPS as a sensing unit of the microelectrochemical analysis system are summarized. Then, the most recent advances in the development of the LAPS analysis system are explained and discussed. In particular, this review focused on the research of ion diffusion, enzymatic reaction, microbial metabolism, and droplet microfluidics using the LAPS analysis system. Finally, the development trends and prospects of the LAPS analysis system are illustrated.

Three-Dimensional (3D) cell culture monitoring: Opportunities and challenges for impedance spectroscopy

Three-dimensional (3D) cell culture has developed rapidly over the past 5-10 years with the goal of better replicating human physiology and tissue complexity in the laboratory. Quantifying cellular responses is fundamental in understanding how cells and tissues respond during their growth cycle and in response to external stimuli. There is a need to develop and validate tools that can give insight into cell number, viability, and distribution in real-time, nondestructively and without the use of stains or other labelling processes. Impedance spectroscopy can address all of these challenges and is currently used both commercially and in academic laboratories to measure cellular processes in 2D cell culture systems. However, its use in 3D cultures is not straight forward due to the complexity of the electrical circuit model of 3D tissues. In addition, there are challenges in the design and integration of electrodes within 3D cell culture systems. Researchers have used a range of strategies to implement impedance spectroscopy in 3D systems. This review examines electrode design, integration, and outcomes of a range of impedance spectroscopy studies and multiparametric systems relevant to 3D cell cultures. While these systems provide whole culture data, impedance tomography approaches have shown how this technique can be used to achieve spatial resolution. This review demonstrates how impedance spectroscopy and tomography can be used to provide real-time sensing in 3D cell cultures, but challenges remain in integrating electrodes without affecting cell culture functionality. If these challenges can be addressed and more realistic electrical models for 3D tissues developed, the implementation of impedance-based systems will be able to provide real-time, quantitative tracking of 3D cell culture systems.