Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter

Microfluidic fluorescence‐activated cell sorters (μFACS) have attracted considerable interest because of their ability to identify and separate cells in inexpensive and biosafe ways. Here a high‐performance μFACS is presented by integrating a standing surface acoustic wave (SSAW)‐based, 3D cell‐focusing unit, an in‐plane fluorescent detection unit, and an SSAW‐based cell‐deflection unit on a single chip. Without using sheath flow or precise flow rate control, the SSAW‐based cell‐focusing technique can focus cells into a single file at a designated position. The tight focusing of cells enables an in‐plane‐integrated optical detection system to accurately distinguish individual cells of interest. In the acoustic‐based cell‐deflection unit, a focused interdigital transducer design is utilized to deflect cells from the focused stream within a minimized area, resulting in a high‐throughput sorting ability. Each unit is experimentally characterized, respectively, and the integrated SSAW‐based FACS is used to sort mammalian cells (HeLa) at different throughputs. A sorting purity of greater than 90% is achieved at a throughput of 2500 events s^?1. The SSAW‐based FACS is efficient, fast, biosafe, biocompatible and has a small footprint, making it a competitive alternative to more expensive, bulkier traditional FACS.     

Design of Diketopyrrolopyrrole (DPP)‐Based Small Molecules for Organic‐Solar‐Cell Applications

After the first report in 2008, diketopyrrolopyrrole (DPP)‐based small‐molecule photovoltaic materials have been intensively explored. The power conversion efficiencies (PCEs) for the DPP‐based small‐molecule donors have been improved up to 8%. Furthermore, through judicious structure modification, DPP‐based small molecules can also be converted into electron‐acceptor materials, and, recently, some exciting progress has been achieved. The development of DPP‐based photovoltaic small molecules is summarized here, and the photovoltaic performance is discussed in relation to structural modifications, such as the variations of donor–acceptor building blocks, alkyl substitutions, and the type of conjugated bridges, as well as end‐capped groups. It is expected that the discussion will provide a guideline in the exploration of novel and promising DPP‐containing photovoltaic small molecules.