Reduction of ice adhesion on nanostructured and nanoscale slippery surfaces

Ice nucleation and accretion on structural surfaces are sources of major safety and operational concerns in many industries including aviation and renewable energy.Common methods for tackling these are active ones such as heating,ultrasound,and chemicals or passive ones such as surface coatings.In this study,we explored the ice adhesion properties of slippery coated substrates by measuring the shear forces required to remove a glaze ice block on the coated substrates.Among the studied nanostructured and nanoscale surfaces[i.e.,a superhydrophobic coating,a fluoropolymer coating,and a polydimethylsiloxane(PDMS)chain coating],the slippery omniphobic covalently attached liquid(SOCAL)surface with its flexible polymer brushes and liquid-like structure significantly reduced the ice adhesion on both glass and silicon surfaces.Further studies of the SOCAL coating on roughened substrates also demonstrated its low ice adhesion.The reduction in ice adhesion is attributed to the flexible nature of the brush-like structures of PDMS chains,allowing ice to detach easily.

Breath monitoring,sleep disorder detection,and tracking using thin-film acoustic waves and open-source electronics

Apnoea,a major sleep disorder,affects many adults and causes several issues,such as fatigue,high blood pressure,liver conditions,increased risk of type II diabetes,and heart problems.Therefore,advanced monitoring and diagnosing tools of apnoea disorders are needed to facilitate better treatment,with advantages such as accuracy,comfort of use,cost effectiveness,and embedded computation capabilities to recognise,store,process,and transmit time series data.In this work we present an adaptation of our apnoea-Pi open-source surface acoustic wave(SAW)platform(Apnoea-Pi)to monitor and recognise apnoea in patients.The platform is based on a thin-film SAW device using bimorph ZnO and Al structures,including those fabricated as Al foils or plates,to achieve breath tracking based on humidity and temperature changes.We applied open-source electronics and provided embedded computing characteristics for signal processing,data recognition,storage,and transmission of breath signals.We show that the thin-film SAW device out-performed standard and off-the-shelf capacitive electronic sensors in terms of their response and accuracy for human breath-tracking purposes.This in combination with embedded electronics makes a suitable platform for human breath monitoring and sleep disorder recognition.

Flexible multifunctional platform based on piezoelectric acoustics for human–machine interaction and environmental perception

Flexible human–machine interfaces show broad prospects for next-generation flexible or wearable electronics compared with their currently available bulky and rigid counterparts.However,compared to their rigid counterparts,most reported flexible devices(e.g.,flexible loudspeakers and microphones)show inferior performance,mainly due to the nature of their flexibility.Therefore,it is of great significance to improve their performance by developing and optimizing new materials,structures and design methodologies.In this paper,a flexible acoustic platform based on a zinc oxide(ZnO)thin film on an aluminum foil substrate is developed and optimized;this platform can be applied as a loudspeaker,a microphone,or an ambient sensor depending on the selection of its excitation frequencies.When used as a speaker,the proposed structure shows a high sound pressure level(SPL)of~90 dB(with a standard deviation of~3.6 dB),a low total harmonic distortion of~1.41%,and a uniform directivity(with a standard deviation of~4 dB).Its normalized SPL is higher than those of similar devices reported in the recent literature.When used as a microphone,the proposed device shows a precision of 98%for speech recognition,and the measured audio signals show a strong similarity to the original audio signals,demonstrating its equivalent performance compared to a rigid commercial microphone.As a flexible sensor,this device shows a high temperature coefficient of frequency of−289 ppm/K and good performance for respiratory monitoring.