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Heating of surface acoustic wave (SAW) devices can be utilized for micro-heating and in microreactor applications, but is a disadvantage in biosensing. In this contribution, we fabricate SAW devices in 128° YX LiNbO3 and ST X quartz substrates with same physical dimensions, having center frequencies approximately of 96 MHz and 78 MHz, respectively to study heating at several power levels. We demonstrate droplet heating is caused by acoustic wave streaming resulting from the coupling between fluid and solid. A 10 μm water droplet on a 128° YX LiNbO3 device can be heated up by 3.3 °C with 15 dbm power level, whereas, the ST X quartz device is only heated up by 0.7°C. Our work illustrates that the 128° YX LiNbO3 substrate shows great potential for liquid heating applications. The ST quartz substrate is better suited for removal of non-specifically bound (NSB) proteins in biosensing applications, especially if shear horizontal SAWs propagating in the orthogonal direction are utilized for biosensing. 

Carcinoembryonic antigen (CEA) is a glycosylphosphatidylinositol cell surface anchored glycoprotein that is a well-known, broad spectrum biomarker related to various cancers and it is also an indicator of disease recurrence. In this work, metal-enhanced fluorescence (MEF) is utilized to lower the detection limit of CEA in immunofluorescence assays. Silver nanocubes (AgNCs) of 50 nm edge-length were incubated to plasmonically enhance fluorescence intensity. This increased sensor sensitivity by a factor of 6 and lowered the limit of detection to below 1 ng/mL in fluorescence detection of the antigen. 

Artificial nano‐ and microswimmers are promising as versatile nanorobots for applications in biomedicine, environmental chemistry, and materials science. Herein, a hybrid micromotor containing a conjugated polymer (poly(3,4‐ethylenedioxythiophene) (PEDOT), and a catalytic structure composed of platinum (Pt) synthesized using a template‐supported electrochemical deposition process is reported. The movement of this PEDOT/Pt micromotor is characterized under chemical power generated by hydrogen peroxide catalysis, and acoustic power generated by surface acoustic waves (SAWs). The acoustic radiation force acting between the bubbles, the secondary Bjerknes force, is shown to increase the micromotor speed. The movement of the micromotor is precisely controllable using the acoustic field, providing excellent response time and reproducibility over a wide dynamic range. A theoretical model is developed to understand and predict the micromotor propulsion under the hybrid chemical and acoustic power. Predicted micromotor speeds are in excellent agreement with experiment as a function of peroxide fuel concentration, SAW field strength, and SAW frequency. The model allows for design of micromotor geometries and acoustic field strengths to achieve desired speed with excellent on/off control.