James Friend

A Rayleigh-Surface Acoustic Waves platform is developed to perform PCR cycles in PDMS wells. The wave is generated from a SiO2/Al/LiNbO3 (128° Y-cut, X direction) structure. Key parameters of the electrode geometry and the well manufacturing are studied to optimize the efficiency, homogeneity and rapidity of the heating. A 25 finger-pairs device with an 8:1 post-cured PDMS well leads to sufficient heating while minimizing evaporation. PCR-mix with glycerol is used to simulate real reaction conditions. With our miniaturized platform, we reach faster heating rates than those of commercially available thermocyclers.

Extracellular vesicles (EVs) show potential for early diagnosis of Alzheimer's disease (AD) and monitoring of its progression. However, EV-based AD diagnosis faces challenges due to the small size and low abundance of biomarkers. Here, we report a fully integrated organic electrochemical transistor (OECT) sensor for ultrafast, accurate, and convenient point-of-care testing (POCT) of serum EVs from AD patients. By utilizing acoustoelectric enrichment, the EVs can be quickly propelled, significantly enriched, and specifically bound to the OECT detection area, achieving a gain of over 280 times response in 30 s. The integrated POCT sensor can detect serum EVs from AD patients with a limit of detection as low as 500 EV particles/mL and a reduced detection time of just two minutes. Furthermore, the integrated POCT sensors were used to monitor AD progression in an AD mouse model by testing the mouse Aβ EVs at different time courses (up to 18 months) and compared with the Aβ accumulation using high-resolution magnetic resonance imaging (MRI). This innovative technology has the potential for accurate and rapid diagnosis of Alzheimer's and other neurodegenerative diseases, and monitoring of disease progression and treatment response.

To understand the mechanisms driving fluid flow behavior in nanofluidics so that they may be used for on-chip biomedical and chemical applications, the fluid's motion itself needs to be observable and measurable, a difficult challenge at these small scales. We present a new method for measuring both slow and fast flows in nanofluidics using high-speed digital holographic microscopy. We measure the evaporation-driven flow in 25 and 7 nm tall nanoslit channels, showing that the consequent flow speed is about 15 times slower than open atmospheric evaporation due to the confinement of the nanoslit channel. We also measured the surface acoustic wave-driven flow in the 25 nm channel, showing flow at a speed of 0.12 m/s from acoustic wave propagation at 39.7 MHz interacting with the fluid in the channel. A process to eliminate the many sources of noise to produce these results is provided, showing that─in particular─spatial averaging is useful to determine the fluid flow and the dewetting of the fluid in the nanoslit channel over time.

Liquid jets in crossflow are common ways of delivering large amounts of fuel in a rapidly atomized form to modern aircraft combustor systems. Unfortunately, they are not able to deliver the necessary droplet sizes for the demands of future advanced propulsion systems without modification. In this study, an ultrasonically excited solid obstruction, or pintile, is added to the liquid jet in crossflow system. This addition is intended to introduce additional instabilities in the liquid jet, improving on jet breakup characteristics across a wide range of Weber numbers. This setup is then subjected to a range of crossflow conditions, while maintaining the momentum flux ratio of the jet, and imaged using Mie scatter techniques in both the streamwise and transverse planes. Lagrangian droplet tracking is applied to the streamwise plane to obtain distributions of droplet sizes, velocities, and droplet generation rates to compare the excited and unexcited liquid jets. The sheet breakup distance is tracked in the transverse plane and compared. Across each condition studied, the introduction of the ultrasonically excited pintile led to improvements in the breakup characteristics of the liquid jet. For low Weber conditions, excitation led to a 45% decrease in average droplet size, and a corresponding 380% increase in droplet production rate. The sheet breakup distance was additionally shortened by more than 25% for each case studied, demonstrating substantial improvement to the inactive pintile, proving to be a strong candidate for next generation fuel injection technologies.

Further enhancements in aircraft engine development will rely in significant part on facile control of fuel spray characteristics like droplet size, size distribution, and intact jet-to-droplet length. Aircraft engines suffer from extreme trade-offs when exceptional performance is needed. For example, high fuel consumption, poor propulsive efficiency, and a significant increase in both noise and a radar-visible exhaust gas plume often accompany high-thrust engine states. We present a novel nozzle pintile design that utilizes a single-crystal piezoelectric ultrasonic device to induce more rapid and complete fuel atomization. Preliminary results of experiments where the liquid sheets are injected into quiescent air show that the device increases the efficiency of fuel burning even in harsh environments resembling that of a combustion engine. Specifically, we show that at Weber numbers applicable to fuel flow rates, the device increases the amount of smaller droplets and shrinks the distribution of droplet sizes. Furthermore, these results appear as the liquid's surface tension decreases. With these promising results, we plan to test design variations.

Introduction It is now known that capillary waves driven upon a fluid interface by high frequency ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mo>&gt;</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math> MHz) ultrasound exhibit capillary wave turbulence: the appearance of waves with phase and wavelength far removed from the excitation signal that drives them. These waves are responsible in significant part for atomization, a useful application for ultrasound, though the physics responsible for their appearance is poorly understood. Methods We use high-speed digital holographic microscopy to observe these capillary waves, an important step towards understanding their generation and atomization phenomena. Results We observe Zakharov-Kolmogorov weak wave turbulence for a limited range of input power, and find broader turbulence phenomena outside this range. We see discrete thresholds as the input power is increased, where higher and higher frequency responses are driven in the capillary waves with sudden onset between regimes. Discussion We employed spatial analysis to find extensions of the capillary wave response to higher frequencies, suggesting there is additional information in the spatial distribution of the capillary wave that is rarely if ever measured. We verified via frequency modulation that nonlinear resonance broadening is present, which undermines the use of Faraday wave or parametric wave theories to characterize these waves, important in the context of atomization which is now, definitively, not a Faraday wave process.

Surface acoustic wave (SAW) generation on 128° YX acoustic superlattice has been investigated by considering the finite-depth of the domain created by the UV direct-domain writing. We found that bound and localized SAW will be generated when the domain depth of the ASL structure, underlying the transducer, is smaller and bigger than the lattice period, respectively. Efficient bound SAW can be achieved, provided the domain depth is 30 % of the lattice period.

We present a new device that effectively reduces the breakup of cylindrical Rayleigh-regime liquid jets in quiescent air. The device is made of lithium niobate, a piezoeletric material, to convert input electrical power into oscillation. A 10x10 mm crystal with a through hole of 1 mm in diameter placed at the outlet of the liquid's nozzle, the device creates 7 MHz acoustic waves that disrupt the stability of the jet. We show its effectiveness over a range of different input powers and Weber and Ohnesorge numbers. Furthermore, we show modelling results in COMSOL and equations that describe this new instability mechanism. This opens new doors for droplet-on-demand applications.

Enzyme-linked immunosorbent assays (ELISAs) are widely used in biology and clinical diagnosis. Relying on antigen–antibody interaction through diffusion, the standard ELISA protocol can be time-consuming, preventing its use in rapid diagnostics. We present a time-saving and more sensitive ELISA without changing the standard setup and protocol, using surface acoustic waves (SAWs) to enhance performance. Each step of the assay is improved principally via acoustic streaming-driven advection. Using SAWs, the time required for one step of an example ELISA is reduced from 60 to 15 min to achieve the same signal intensity. By extending the duration of SAW exposure to 20 min, the binding amount can be significantly improved over the 60 min, 35 °C ELISA without SAWs. When introducing SAWs to the bead-based ELISA, the time required for binding can be further reduced to 2 min due to increasing depletion zone by acoustic streaming on beads surface. The sensitivity of ELISA can be significantly increased with lower LoD by combination of SAW stimulation and ultrabright fluorescent nanoscale labels. By significantly increasing the speed and sensitivity of ELISA, its utility may be improved for a wide range of point-of-care diagnostics applications.

In recent years, the need for accurate analysis of acoustic streaming has become urgent, as classical methods fail to quantify flows generated by acoustic waves beyond a few hundred kHz. This problem, identified since Lighthill’s seminal 1978 namesake publication, remains unresolved. Researchers, including myself, have relied on computational analysis and approximations to address some of these challenges. Few have examined the dynamic behavior of acoustic streaming—such as delayed onset, response to inharmonic excitation, and flows sustained after the acoustic wave stops—despite their importance in experiments. The difficulty lies in analyzing these flows. However, after extensive work on an alternative approach, we now have a method for closed-form analysis of one-dimensional acoustic streaming that includes transient behavior and accounts for nonlinear compressibility and viscous effects. We offer a coherent and straightforward plan for analyzing simple acoustic streaming cases where classical theories fail. This method can model both steady-state and transient acoustic streaming, potentially eliminating the need for computational analysis and providing enough physical insight for design purposes. Our goal is to equip listeners with the tools to perform this analysis themselves without need for tedious computational methods.

Porous media provides numerous useful capabilities, including absorption, filtration, separation, and large surface areas for reactions and diagnostics. Acoustofluidic techniques have been tentatively explored to enhance flow in such media, but the majority of such work has problems, including flows that bypass the medium, irregular pores, slow or opposing flows, and non-directional random flow. Of particular interest is the porous material's significant acoustic losses; therefore, attenuation is greater when pore dimensions are small and non-directional. In this work, we drive fluids through randomly oriented pores as small as 12 micrometers. Acoustic streaming phenomena generated by the attenuation of traveling surface acoustic waves in the medium are used to pump the fluid. The media is carefully laminated with the sides sealed to facilitate flow solely through the media. The flow rates generated by a unique floating electrode unidirectional transducer (FEUDT) are compared with a typical interdigital transducer. Because the FEUDT is specifically designed to continuously generate unidirectional acoustic waves, we show that the flow is 3 times faster than the diffusion rate. Furthermore, we reveal new evidence of homogeneous mixing caused by acoustic streaming inside the porous media.

Her primary education research interests include experiential learning, holistic modeling, and active learning practices.In the last decade, she has dedicated her education efforts towards developing new experiential learning curriculum, creating preparation programs to address opportunity gaps, and enhancing involvement of student organizations in engineering education.Her academic research interest includes include sensing, sensors, soft materials, wearable sensors, and remote health monitoring/devices, where she has spent the last seven years

Enzyme-linked immunosorbent assays (ELISAs) are widely used in biology and clinical diagnosis. Relying on antigen-antibody interaction through diffusion, the standard ELISA protocol can be time-consuming, preventing its use in rapid diagnostics. We present a time-saving and more sensitive ELISA without changing the standard setup and protocol, using surface acoustic waves (SAWs) to enhance performance. Each step of the assay, from the initial antibody binding onto the walls of the well plate to the target analyte molecules' binding for detection─except, notably, for the blocking step─is improved principally via acoustic streaming-driven advection. Using SAWs, the time required for one step of an example ELISA is reduced from 60 to 15 min to achieve the same binding amount. By extending the duration of SAW exposure to 20 min, the sensitivity can be significantly improved over the 60 min, 35 °C ELISA without SAWs. It is also possible to confer beneficial improvements to bead-based ELISA by combining it with SAWs to further reduce the time required for binding to 2 min. By significantly increasing the speed of ELISA, its utility may be improved for a wide range of point-of-care diagnostics applications.

Alzheimer's disease (AD) is a debilitating condition that affects millions of people worldwide. One promising strategy for detecting and monitoring AD early on is using extracellular vesicles (EVs)-based point-of-care testing; however, diagnosing AD using EVs poses a challenge due to the low abundance of EV-biomarkers. Here, we present a fully integrated organic electrochemical transistor (OECT) that enables high accuracy, speed, and convenience in the detection of EVs from AD patients. We incorporated self-aligned acoustoelectric enhancement of EVs on a chip that rapidly propels, enriches, and specifically binds EVs to the OECT detection area. With our enhancement of pre-concentration, we increased the sensitivity to a limit of detection of 500 EV particles/μL and reduced the required detection time to just two minutes. We also tested the sensor on an AD mouse model to monitor AD progression, examined mouse Aβ EVs at different time courses, and compared them with intraneuronal Aβ cumulation using MRI. This innovative technology has the potential to diagnose Alzheimer's and other neurodegenerative diseases accurately and quickly, enabling monitoring of disease progression and treatment response.

OBJECTIVE: Identify infants with abnormal suckling behavior from simple non-nutritive suckling devices. BACKGROUND: While it is well known breastfeeding is beneficial to the health of both mothers and infants, breastfeeding ceases in 75 percent of mother-child dyads by 6 months. The current standard of care lacks objective measurements to screen infant suckling abnormalities within the first few days of life, a critical time to establish milk supply and successful breastfeeding practices. MATERIALS AND METHODS: A non-nutritive suckling vacuum measurement system, previously developed by the authors, is used to gather data from 91 healthy full-term infants under thirty days old. Non-nutritive suckling was recorded for a duration of sixty seconds. We establish normative data for the mean suck vacuum, maximum suck vacuum, suckling frequency, burst duration, sucks per burst, and vacuum signal shape. We then apply computational methods (Mahalanobis distance, KNN) to detect anomalies in the data to identify infants with abnormal suckling. We finally provide case studies of healthy newborn infants and infants diagnosed with ankyloglossia. RESULTS: In a series of case evaluations, we demonstrate the ability to detect abnormal suckling behavior using statistical analysis and machine learning. We evaluate cases of ankyloglossia to determine how oral dysfunction and surgical interventions affect non-nutritive suckling measurements. CONCLUSIONS: Statistical analysis (Mahalanobis Distance) and machine learning [K nearest neighbor (KNN)] can be viable approaches to rapidly interpret infant suckling measurements. Particularly in practices using the digital suck assessment with a gloved finger, it can provide a more objective, early stage screening method to identify abnormal infant suckling vacuum. This approach for identifying those at risk for breastfeeding complications is crucial to complement complex emerging clinical evaluation technology. CLINICAL IMPACT: By analyzing non-nutritive suckling using computational methods, we demonstrate the ability to detect abnormal and normal behavior in infant suckling that can inform breastfeeding intervention pathways in clinic.Clinical and Translational Impact Statement: The work serves to shed light on the lack of consensus for determining appropriate intervention pathways for infant oral dysfunction. We demonstrate using statistical analysis and machine learning that normal and abnormal infant suckling can be identified and used in determining if surgical intervention is a necessary solution to resolve infant feeding difficulties.

Ultrasound has been used to modulate neural activity in rodents and primates; however, combining ultrasound stimulation with in vivo imaging in freely moving animals has been challenging. Here, we design and validate a transducer to overcome these challenges in the rodent. We develop a head-mounted ultrasound transducer that can be combined with a fiber photometry system. This combination allows us to monitor ultrasound-evoked responses in striatal neurons in awake and freely moving animals. Together, this system allows for a high-resolution analysis of ultrasound-evoked biology at the level of both neural circuits and behavior in freely moving animals, critical to providing a mechanistic understanding of ultrasound neuromodulation.

Endovascular techniques have revolutionized the treatment of cerebrovascular disease in the human brain. In this review, we examine the current state of this technology, which consists of multiple concentric catheters that are manually navigated from the lumen of peripheral arterial access within the patient's arm or leg up into the brain using fluoroscopic image guidance. There is tremendous potential for the fields of robotics, materials science, and computer science to redefine the current techniques and ultimately improve the safety and efficacy of treatments.

We study a fifty-year-old problem of fast acoustic streaming, that is, the generation of moderate or large hydrodynamic Reynolds number ( $\textit {Re}$ ) acoustic streaming (or steady flow) by the convection of momentum in an acoustic wave (or another periodic flow), while the latter is simultaneously altered by the former. The intrinsic disparity of length and time scales makes a brute-force solution of the full Navier–Stokes and continuity equations a formidable problem. Circumventing this difficulty, we split the problem into a time-averaged system of equations for the steady flow component and a dynamic system of equations for its quasi-periodic flow counterpart. The latter system of equations is obtained by subtracting the time-averaged Navier–Stokes equation from its original dynamic form, and is rendered a nonlinear wave equation using the continuity equation and an adiabatic connection between density and pressure. The resulting equations are compatible with the theory by Eckart for small $\textit {Re}$ flow, and capture large- $\textit {Re}$ effects. Scaling analysis and a case study show that acoustic streaming is weak and does not contribute to the acoustic wave close to the wave source, relevant to many microfluidic systems. At small $\textit {Re}$ , the streaming magnitude is proportional to an inverse Strouhal number, a small quantity in experiments. Moderate and large $\textit {Re}$ render the streaming magnitude comparable to the pre-attenuating periodic flow (or particle velocity of the wave) at approximately a wave attenuation length away from the wave source or further; the wave is altered by the streaming that it generates, and the streaming dominates the flow far from the wave source.

Mechanisms by which electric (E) or magnetic (B) fields might be harnessed to affect tumor cell behavior remain poorly defined, presenting a barrier to translation. We hypothesized in early studies that the glycocalyx of lung cancer cells might play a role in mediating plasma membrane leak by low-frequency pulsed magnetic fields (Lf-PMF) generated on a low-energy solenoid platform. In testing glioblastoma and neuroblastoma cells known to overexpress glycoproteins rich in modifications by the anionic glycan sialic acid (Sia), exposure of brain tumor cells on the same platform to a pulse train that included a 5 min 50Hz Lf-PMF (dB/dt ∼ 2 T/s at 10 ms pulse widths) induced a very modest but significant protease leak above that of control nonexposed cells (with modest but significant reductions in long-term tumor cell viability after the 5 min exposure). Using a markedly higher dB/dt system (80 T/s pulses, 70 μs pulse-width at 5.9 cm from a MagVenture coil source) induced markedly greater leak by the same cells, and eliminating Sia by treating cells with AUS sialidase immediately preexposure abrogated the effect entirely in SH-SY5Y neuroblastoma cells, and partially in T98G glioblastoma cells. The system demonstrated significant leak (including inward leak of propidium iodide), with reduced leak at lower dB/dt in a variety of tumor cells. The ability to abrogate Lf-PMF protease leak by pretreatment with sialidase in SH-SY5Y brain tumor cells or with heparin lyase in A549 lung tumor cells indicated the importance of heavy Sia or heparan sulfate glycosaminoglycan glycocalyx modifications as dominant glycan species mediating Lf-PMF membrane leak in respective tumor cells. This "first-physical" Lf-PMF tumor glycocalyx event, with downstream cell stress, may represent a critical and "tunable" transduction mechanism that depends on characteristic anionic glycans overexpressed by distinct malignant tumors.

It is now known that capillary waves driven upon a fluid interface by high frequency ($&gt;1$~MHz) ultrasound exhibit capillary wave turbulence: the appearance of waves with phase and wavelength far removed from the excitation signal that drives them. An important step towards understanding atomization phenomena driven in this system, these capillary waves may now be studied using high-speed digital holographic microscopy. We observe Zakharov-Kolmogorov weak wave turbulence for a limited range of input power, and find broader turbulence phenomena outside this range. We see discrete thresholds as the input power is increased, where higher and higher frequency responses are driven in the capillary waves with sudden onset between regimes. Here, we employ spatial analysis to find one such extension of the capillary wave response to higher frequencies, suggesting there is additional information in the spatial distribution of the capillary wave that is rarely if ever measured. We verify via frequency modulation that nonlinear resonance broadening is present, which undermines the use of Faraday wave or parametric wave theories to characterize these waves, important in the context of atomization which is not a Faraday wave process.

The propagation of acoustic waves in fluids and solids produces fascinating phenomena that have been studied since the late 1700s and through to today, where it is finding broad application in manipulating fluids and particles at the micro to nano-scale. Due to the recent and rapid increase in application frequencies and reduction in the scale of devices to serve this new need, discrepancies between theory and reality have driven new discoveries in physics that are underpinning the burgeoning discipline. While many researchers are continuing to explore the use of acoustic waves in microfluidics, some are exploring vastly smaller scales, to nanofluidics and beyond. Because many of the applications incorporate biological material—organelles, cells, tissue, and organs—substantial effort is also being invested in understanding how ultrasound interacts with these materials. Surprisingly, there is ample evidence that ultrasound can be used to directly drive cellular responses, producing a new research direction beyond the established efforts in patterning and agglomerating cells to produce tissue. We consider all these aspects in this mini-review after a brief introduction to acoustofluidics as an emerging research discipline.

We find capillary wave turbulence (WT) spanning multiple dynamical regimes and geometries, all within a 40μL volume microfluidic system. This study is made viable with recent advances in ultra-high-speed digital holographic microscopy, providing 10μs time and 10nm spatial resolutions for images across the entire field at speeds sufficient to capture the salient wave phenomena. The observed WT types are: (i) discrete wave turbulence (DWT) dominated by finite domain effects, (ii) kinetic wave turbulence (KWT) that approximately satisfies weak wave turbulence (WWT) theory, and (iii) intermediate wave turbulence (IWT) that exhibits features from both DWT and KWT. We show that WT regime depends on input power and wavenumber, and we provide simple nondimensional parameters – derived from WWT theory – for intra-spectrum regime classification. Using the nondimensional parameters, a bulk nonlinearity metric is defined that employs bicoherence-based weighting. Analysis of experimental results reveals a correspondence between the theoretical regime classifiers and the observed phenomena. At sufficiently high input powers, the phenomena substantially depart from the WWT theory and reveal a regime of strongly nonlinear wave turbulence (SWT) defined by shallower spectral slopes that achieve a constant slope value over a range of input powers. This may suggest a corresponding power-law solution to the governing equations. This work augments current understanding of WT regimes and behaviors, and directly applies to many fields beyond fluid mechanics. For example, SWT appears upon the fluid interface at powers less than required for atomization, indicating that further study of SWT is needed to properly understand ultrasound-driven fuel spray atomization and drug and agricultural nebulization.

High Resolution Image Download MS PowerPoint Slide Remarkably, the interface of a fluid droplet will produce visible capillary waves when exposed to acoustic waves. For example, a small (∼1 μL) sessile droplet will oscillate at a low ∼10 2 Hz frequency when weakly driven by acoustic waves at ∼10 6 Hz frequency and beyond. We measured such a droplet’s interfacial response to 6.6 MHz ultrasound to gain insight into the energy transfer mechanism that spans these vastly different time scales, using high-speed microscopic digital transmission holography, a unique method to capture three-dimensional surface dynamics at nanometer space and microsecond time resolutions. We show that low-frequency capillary waves are driven into existence via a feedback mechanism between the acoustic radiation pressure and the evolving shape of the fluid interface. The acoustic pressure is distributed in the standing wave cavity of the droplet, and as the shape of the fluid interface changes in response to the distributed pressure present on the interface, the standing wave field also changes shape, feeding back to produce changes in the acoustic radiation pressure distribution in the cavity. A physical model explicitly based upon this proposed mechanism is provided, and simulations using it were verified against direct observations of both the microscale droplet interface dynamics from holography and internal pressure distributions using microparticle image velocimetry. The pressure-interface feedback model accurately predicts the vibration amplitude threshold at which capillary waves appear, the subsequent amplitude and frequency of the capillary waves, and the distribution of the standing wave pressure field within the sessile droplet responsible for the capillary waves.

The latest advances in topological physics have yielded a toolset for highly robust wave-propagation modalities for overcoming obstacles involving beam steering and lateral diffraction in surface acoustic waves (SAWs). However, extant proposals are limited to the exploitation of spin- or valley-polarized phases and rely on nonzero Berry curvature effects. Here, we propose and experimentally demonstrate a highly robust guiding principle, which instead employs an intrinsic chirality of phase vortices and maintains a zero Berry curvature for SAWs. Based on a line defect within a true triangular phononic lattice, the guided SAW mode spans a wide bandwidth [(\ensuremath{\Delta}\ensuremath{\omega}/\ensuremath{\omega}${}_{\mathrm{center}}$) \ensuremath{\sim} 10%] and is well confined in the lateral direction with 3-dB attenuation within half of a unit cell. SAW routing around sharp bends with negligible backscatter is demonstrated. The on-chip integrated design permits unidirectional SAW modes that can enable considerable miniaturization of SAW-based devices, with applications ranging from radio-frequency devices to quantum information transduction.

Over the years, a diverse range of physical and chemical phenomena have been explored and applied to devise reliable, small thrusters for stationkeeping and orientation of spacecraft. Commercial space flight is accelerating this need. Here, we consider acoustically driven melting of a frozen working fluid in the nozzle of an acoustic device, followed by acoustofluidic atomization from the nozzle to produce thrust. Fifty-five MHz acoustic waves generated by piezoelectric transducers couple into liquid and transfer energy in the form of both acoustic radiation and streaming, producing a directed atomized spray. A challenge in this system, as with most liquid-thrust systems, is the risk of phase change due to the extreme thermal environment in space, particularly in the freezing of the working fluid. Though acoustic energy is known to produce rapid and controllable heating, it so far has not been used to produce phase changes. The atomization produces capillary pressure sufficient to draw in fluid from a reservoir, though we do use a simple pressure-driven pump to support greater atomization rates. We provide a simple energy conservation model to explain the acoustothermal interaction and validate this with experiments. The specific impulse and thrust of this type of thruster are quite modest at 0.1–0.4 s and 12.3 μN, respectively, but the thruster component is small, light, and is without moving parts, a fascinating potential alternative to current technologies.