publications

Biohybrid robots actuated by living skeletal muscles are capable of adaptive functional behaviors and could enable future applications ranging from precision microsurgery to unmanned exploration.

Skeletal muscle-powered robots typically rely on 3D tissues which require large cell volumes and offer limited control of muscle fiber alignment. Here, we present a method for fabricating 2D monolayers, or thin films, of skeletal muscle on micropatterned hydrogel skeletons. We vary skeleton design parameters to optimize fiber alignment and resultant actuation forces and strokes. Our optimized designs generate mN-scale forces and mm-scale force strokes from cm-scale tissues, significantly outperforming previous 2D skeletal muscle actuators and improving untethered longevity by ∼4500× from < 10 min to > 30 days. Moreover, such thin films increase force density (contractile force per unit tissue volume) by 20X as compared to 3D muscles, thus significantly increasing efficiency. We leverage optimized skeletal muscle thin films to power a multi-limbed robot with independent fins capable of on/off and frequency-dependent speed control. With these control inputs, we achieve steered multi-directional locomotion at speeds up to 4 body lengths per minute in straight movement and 1200 degrees per minute in rotational movement, highlighting potential for such actuators to power long-lasting functional robots.

Spheroids are important 3D multicellular culture systems that recapitulate key structural and functional features of native tissues.

However, label-free long-term and precise manipulation of spheroids in culture environments remains challenging. Here, we report a donut-shaped magnetic millirobot (DonutBot) controlled by permanent magnetic traps for wireless pick-and-place of individual tumor spheroids. The DonutBot is fabricated from magnetic calcium–alginate hydrogel, exhibiting excellent cytocompatibility. A strong in-plane magnetic trap is established by combining two opposing permanent magnet arrays. Under in vitro culture conditions, stable robot trapping is realized without external energy input or heat generation, ensuring secure positioning of the spheroid. The trapping force steadily holds the spheroid upon regular exchange of cell culture media. By integrating in-plane control and dynamic vertical control, the DonutBot enables automated pick-and-place manipulation of PANC-1 pancreatic tumor spheroids along designed trajectories. The miniature robotic manipulation system allows for continuous and precise spheroid manipulation under physiologically relevant conditions, offering new opportunities for long-term studies of spheroid mechanobiology.

Nanoscale mechano-optical surfaces enable electronics-free strain sensing, attractive for skin-interfaced devices, yet reported implementations require laser/spectrometer interrogation, negating this advantage.

Here, we report electrically passive mechanical transduction of arterial pulsation into diffractive colour shifts read by unmodified smartphone cameras, enabled by a dual-function monolithic poly-dimethylsiloxane (PDMS) film. Using large-area double-sided nanoimprinting, we achieve a strain-sensitive nanophotonic surface on one face of the film and a bio-inspired 3D structural adhesive on the other. We measure strain-dependent optical response and reproduce it in color-mixing optical simulations. In uniaxial cyclic loading tests, 2% strain produces a 9% RGB-intensity modulation, stable over 1000 cycles. Further, 3D structuring improves adhesive shear strength by 65% on skin over flat PDMS. Hand-held smartphone recordings in humans (n = 13) resolve sub-beat hemodynamics in agreement with clinical reference (per-beat waveform ρ = 0.94 ± 0.03), exceeding established non-invasive techniques such as active reflectance photoplethysmography (PPG), imaging PPG, and piezoelectric pulse-force sensors in simultaneous recordings. Importantly, mechanical transduction at the elastomer–air interface presents an optical cardiovascular monitoring approach agnostic to dermal-melanin, a known PPG confounder. Together, these advances establish camera-readable mechanochromic elastomers as versatile materials platforms for wearable cardiovascular monitoring, point-of-care diagnostics, and electronics-free human-machine interfaces.

The skin as the largest human organ serves several functions, such as natural protection against internal as well as external environmental influences.

Three-dimensional (3D)-tissue engineering has emerged as a promising approach for the development of functional and physiologically relevant dermis substitutes. Mimicking the topography of the dermis to develop a skin-niche model (SKN) that contains epidermal stem cells is still a challenge. This study aimed to develop a dermis equivalent featuring a physiologically relevant dermal-epidermal junction (DEJ) topography; hence, a pattern was printed using 2-photon polymerization (2PP). The depth of the invaginations can influence cell differentiation and proliferation of epidermal stem cells. The template was subsequently translated into a dermis equivalent (DE). The human neonatal dermal fibroblasts (HDFn) remodeled the DE over 14 days, resulting in reduced dimensions that remained within the physiological range. The DE contains gelatin methacrylate (GelMA) and proliferating fibroblasts that produce extracellular matrix (ECM). In a proof-of-concept, N/TERT-1 keratinocytes, as the epidermal layer, were seeded on the patterned DE to verify the adhesion and proliferation of keratinocytes on the DE. Overall, this approach enables the generation of a DE with a natural DEJ, as a more physiological skin model for future use in disease modeling, drug development, screening, and skin transplantation.

Nature achieves extraordinary mechanical performance by precisely regulating β-structure formation in proteins such as fibroin, elastin, and resilin. 

Replicating this level of structural control remains a major challenge in protein engineering. Here, we integrate biomimetic design with deep learning–guided de novo protein engineering to create environmentally responsive β-hairpin peptides. Computational optimization enhanced β-hairpin propensity, hydrophilicity, and solvent accessibility while preserving high aqueous solubility. The peptides remain intrinsically disordered in solution but rapidly undergo a β-hairpin transition upon exposure to minimal concentrations of sodium dodecyl sulfate (SDS), a model amphiphilic trigger. This structural conversion drives assembly into mechanically reinforced materials exhibiting increased stiffness and hardness relative to the unfolded state. Our findings provide mechanistic insight into regulated β-structure formation and demonstrate a scalable strategy for programming environmentally triggered protein folding, hierarchical assembly, and mechanical function, opening new opportunities for the rational design of next-generation adaptive biomaterials.

Shape memory behavior in engineered systems is traditionally achieved through material-level phase transformations or polymer network rearrangements.

While effective, these approaches tightly couple functionality to chemistry, limiting scalability, material choice, and manufacturing flexibility. An alternative paradigm is to embed recoverability within structural architecture itself, decoupling actuation from intrinsic material phase changes. We present a feather-inspired phase-transforming cellular material–spring system (F-PXCM) that achieves shape recovery through structural interactions rather than active phases. PXCMs, designed with bistable sinusoidal geometries, mimic the hydration-induced softening of the feather matrix, while temperature-invariant springs replicate keratinous fibers. Finite element simulations show that thermal softening of PXCMs, combined with spring restitution, enables complete recovery, while additive-manufactured prototypes confirm the computational results. Exploratory microscale fabrication with two-photon polymerization highlights key challenges and pathways forward.

Free-standing thin liquid films offer a convenient way to probe matter in solution without a substrate, where a small sample thickness is required.

The production of thin films in a vacuum environment is required for probes that cannot penetrate through a surrounding gas or in cases where the gas produces problematic background noise. Nozzles that produce continuously flowing liquid sheet jets have been employed recently for scattering and spectroscopy measurements at X-ray free-electron lasers (XFELs). However, their performance in vacuum with aqueous samples is complicated by high freezing susceptibility due to a strong evaporative cooling effect. Here, we introduce a vacuum-compatible gas-impinging liquid sheet jet nozzle capable of generating sub-100 nm aqueous films. The introduction of a second axisymmetric helium gas sheath surrounding the liquid orifice enables seamless startup and shutdown within a vacuum environment. We investigated the sheet geometry dependence under varying flow conditions and liquid viscosity and demonstrated its viability for X-ray scattering measurements at a high-repetition-rate XFEL source. Finally, we present potential strategies for reducing sample consumption. Our findings confirm that this nozzle exhibits simplified vacuum operation and may help promote the broader utilization of liquid sheet jets for several experimental applications.

AM enables the design of compliant mechanisms that encode functions directly into geometry. Existing DfAM frameworks rarely address microscale AM, such as two-photon polymerisation (2PP).

We present the design process of an airtight, monolithic bellows structure in rigid 2PP resin that serves both as a sensor and an actuator. Through co-evolution of problem and solution, we identify 2PP-specific design considerations and opportunities, including fabrication uncertainties, cross-scale iteration, and design for post-processing, contributing to a case-based DfAM framework for microscale AM.

Diagnosing gastrointestinal (GI) diseases affecting the small intestine is a prevalent healthcare challenge as traditional procedures require sedation and have limited small intestinal access.

Ingestible capsule technologies have emerged as a promising minimally-invasive alternative to endoscopic procedures, offering access to the entire GI tract. However, biopsy capsules have yet to translate clinically due to their external stimulation or power requirements. Here, an ingestible low-power thermomechanical gear-train actuation system featuring a hybrid 3D-printed tissue scraper is demonstrated. The system easily interfaces with ingestible capsule-based electronics for on-command activation with a power requirement of 150-180 mW, a ~40-80% power reduction compared to previously demonstrated prototypes. The tissue scraper features a 1 μ m blade requiring 0.208±0.053 N to penetrate phantom tumor tissue to a 500 μ m depth. An average output force of 2.5±0.8 N was demonstrated by the system, surpassing the necessary penetration force. Testing on ex vivo tissue showed a collection volume of 1.5±1.2 mm³ which is relevant for histological and genetic analysis. The device was integrated with ingestible electronics which wirelessly initiate activation; a necessary capability for future feedback-driven sampling. Overall, the biopsy system represents an advance toward autonomous small intestinal tissue biopsy, introducing a new paradigm for GI disease diagnosis. 

Flow past obstacle clusters in micro-channels is central to a wide range of microfluidic applications, yet its fundamental hydrodynamics remain poorly understood under strong geometric confinement.

No-slip boundary conditions on all walls enforce inherently three-dimensional (3D) flow structures in fully confined micro-channels, fundamentally altering wake formation, momentum transport, and drag mechanisms. A combined experimental and numerical investigation of wake dynamics behind obstacle clusters in laminar micro-channel flows is presented. High-resolution micro-particle image velocimetry and resolved 3D computational fluid dynamics simulations are employed to systematically explore the effects of Reynolds number and cluster porosity. We demonstrate that full wall confinement suppresses classical wake–regime transitions commonly observed in shallow and unconfined flows, including shear layer instabilities and vortex shedding. Instead, wake recovery is governed primarily by secondary flows that promote rapid momentum redistribution across the channel depth. As a result, wake length exhibits only weak dependence on Reynolds number and is controlled predominantly by cluster porosity. We further introduce the relative bleeding velocity as a unifying metric to characterize the transition from macro-particle to individual particle behavior. The relative bleeding velocity is the ratio of the mean velocity through the cluster’s main axis perpendicular to the inflow and the mean inflow velocity. These findings establish a distinct physical regime of confined wake flows, bridging the gap between classical shallow flow theory and microfluidic hydrodynamics, and provide a foundation for improved prediction of pressure losses, transport, and mixing in micro-reactors and porous microfluidic systems.

Efficient mixing in microfluidic systems is bottlenecked by laminar flow and diffusion-dominated transport, limiting the performance of biochemical assays such as conversion rates of enzymatic processes. Here, we present an acoustofluidic micromixer based on two-photon polymerization (2PP)-printed three-dimensional microneedles that act as ultrasonic microresonators to generate localized acoustic streaming. The freeform arrangement of the microneedles enables integration into diverse microfluidic channel layouts and produces strong, tunable streaming vortices that enhance transport. We characterize the streaming flow fields as a function of actuation frequency, and demonstrate rapid and voltage-dependent mixing with a 2.5-fold enhancement. When applied to the alkaline phosphatase–fluorescein diphosphate (ALP–FDP) reaction, acoustic mixing doubles the fluorescein signal under optimal conditions and significantly reduces the assay time and channel footprint required in continuous flow. These resultsdemonstrate that 3D microneedle-based acoustofluidics is a compact, versatile, and integrable solution for enhancing transport-limited biochemical processes in lab-on-a-chip systems.

Magnetic remote actuation of soft materials is attractive for applications such as transforming materials and medical robots. However, due to manufacturing limitations, microscale magnetoactive devices are scarce and light-based additive manufacturing methods, despite achieving microscale resolution, struggle with particle-induced light scattering. Moreover, large hard-magnetic microparticles restrict ultimate feature sizes and deformation of soft-magnetic nanoparticle composites requires impractically high loading and field gradients. Among successfully fabricated microscale soft-magnetic composites, limited control over particle loading, distribution, and matrix-phase stiffness has hindered their functionality. Here, we combine two-photon polymerization with iron oxide nanoparticle co-precipitation to fabricate 3D-printed microscale nanocomposites with spatially tunable nanoparticle distribution. We controlled nanoparticle content by locally modulating the two-photon dose, imbuing parts with varied magnetic functionality and achieving millimeter-scale elastic deformations, demonstrated by a soft robotic gripper and a bistable bit register and sensor. Our approach enables precise control of mechanical and magnetic properties toward microscale metamaterial and robotics applications.

Magnetic remote actuation of soft materials is attractive for applications such as transforming materials and medical robots. However, due to manufacturing limitations, microscale magnetoactive devices are scarce and light-based additive manufacturing methods, despite achieving microscale resolution, struggle with particle-induced light scattering. Moreover, large hard-magnetic microparticles restrict ultimate feature sizes and deformation of soft-magnetic nanoparticle composites requires impractically high loading and field gradients. Among successfully fabricated microscale soft-magnetic composites, limited control over particle loading, distribution, and matrix-phase stiffness has hindered their functionality. Here, we combine two-photon polymerization with iron oxide nanoparticle co-precipitation to fabricate 3D-printed microscale nanocomposites with spatially tunable nanoparticle distribution. We controlled nanoparticle content by locally modulating the two-photon dose, imbuing parts with varied magnetic functionality and achieving millimeter-scale elastic deformations, demonstrated by a soft robotic gripper and a bistable bit register and sensor. Our approach enables precise control of mechanical and magnetic properties toward microscale metamaterial and robotics applications.

Magnetic remote actuation of soft materials is attractive for applications such as transforming materials and medical robots. However, due to manufacturing limitations, microscale magnetoactive devices are scarce and light-based additive manufacturing methods, despite achieving microscale resolution, struggle with particle-induced light scattering. Moreover, large hard-magnetic microparticles restrict ultimate feature sizes and deformation of soft-magnetic nanoparticle composites requires impractically high loading and field gradients. Among successfully fabricated microscale soft-magnetic composites, limited control over particle loading, distribution, and matrix-phase stiffness has hindered their functionality. Here, we combine two-photon polymerization with iron oxide nanoparticle co-precipitation to fabricate 3D-printed microscale nanocomposites with spatially tunable nanoparticle distribution. We controlled nanoparticle content by locally modulating the two-photon dose, imbuing parts with varied magnetic functionality and achieving millimeter-scale elastic deformations, demonstrated by a soft robotic gripper and a bistable bit register and sensor. Our approach enables precise control of mechanical and magnetic properties toward microscale metamaterial and robotics applications.

In this work, we demonstrate the fabrication as well as immediate application of 3D printed spiral phase plates on the ends of FC/PC fiber adapter ferrule tips using a NanoOne 1000 two-photon polymerization 3D printer from UpNano. The spiral phase plates were fabricated to alter the orbital angular momentum of incoming light, and a direct application of modal filtering in an indoor, short-range, free-space optical communication link was shown. The mode conversion quality of six different 3D printed spiral phase plates on ferrule tips is presented. An l=4 and an l=−4 spiral phase plate were chosen to demonstrate the ability to suppress an aggressing Gaussian signal in a free-space communication link, with the l=4 being printed on a FC/PC ferrule tip used as the transmit, and the l=−4 printed on a glass slide in the receive architecture of the system. Multiple iterations of the experiment were performed, and it was found that the 3D printed structures were able to suppress the aggressing Gaussian beam on average by approximately 32.7 dB and allowed for error-free communication at 10 Gbps on a vortex beam with the co-propagating aggressor at an identical wavelength to the communication link.

Diseases or injuries that affect neuromuscular tissues severely impact human health, motivating the development of in vitro models of the motor control system. Current platforms either have limited reproducibility or require complex fabrication protocols that preclude high-resolution imaging and scalable functional analysis. We have developed a one-step method for fabricating an all-hydrogel limb-on-a-chip that addresses key challenges of current systems by enabling reproducible and scalable manufacturing of neuromuscular tissues compartmentalized into “spinal cord” and “limb” chambers. Co-cultures of motor neurons and skeletal muscles within this platform enable longitudinal tracking of neuromuscular junction formation and visualization of changes in muscle contraction in response to motor neuron stimulation. We demonstrate tissue-wide recordings of muscle force and single-cell-resolution measurements of muscle calcium activity. Our accessible method for fabricating reproducible in vitro neuromuscular models that are compatible with high-resolution imaging and functional readouts provides a powerful tool for investigating the neuromuscular interface in health and disease.

Surface modifications of polycaprolactone (PCL) implants influence osseointegration by altering cell adhesion, proliferation, and differentiation. Osteon-like microtopography has been shown to enhance these parameters compared to untreated PCL. Additional treatments, such as cold atmospheric plasma (CAP) and extracellular matrix (ECM) coatings, may further improve bioactivity. This study evaluates and compares the osteogenic potential of osteon-like microtopography, CAP treatment on non-microstructured PCL, ECM coating on non-microstructured PCL, and their combination. Modified PCL samples were analyzed for cell adhesion, proliferation, and differentiation using primary human mesenchymal stem cells. Compared to osteon-like microtopography, CAP-treated and ECM-coated surfaces the combination of all three increased cell adhesion by nearly two-fold. Cell proliferation followed a similar trend, with the combination treatment showing the greatest enhancement by day 10. Alkaline phosphatase activity peaked with osteon-like microtopography, while mineralization was maximized with the combination treatment. In summary, the integration of osteon-like microtopography with CAP treatment and ECM coating synergistically improves cell adhesion, proliferation, and differentiation, offering a promising strategy for optimizing PCL implants to improve osseointegration.

Endovascular interventions—i.e., minimally invasive procedures that involve navigating guidewires and/or microcatheters through a patient’s vasculature to access target treatment sites—have emerged as a preferable alternative to traditional open surgery in many clinical contexts. Unfortunately, maneuverability constraints inherent to conventional guidewire-microcatheter systems can hinder effective navigation to target sites, elevating the risk of procedural complications or failed catheterization. Soft robotic surgical instruments that harness fluidic actuation schemes hold unique promise to overcome such challenges; however, manufacturing-induced limitations remain a critical barrier to their miniaturization, reproducibility, and clinical translation. To address these issues, in this work, a novel additive manufacturing strategy is presented to realize fluidically steerable soft robotic microcatheters via “two-photon direct laser writing (DLW)”. As an exemplar relevant to 3-French (1 mm-in-diameter) microcatheters used for transarterial chemoembolization (TACE), a 3D-printed soft microrobotic tip is fabricated, which enables localized steering driven by microfluidic inputs while simultaneously facilitating fluidic payload delivery through a central lumen. By providing a pathway to new classes of soft robotic microsurgical instruments that enable on-demand steerability via fluidic means, the presented strategy offers notable potential for navigating narrow, complex, tortuous, and/or delicate vasculature to enhance the safety and efficacy of endovascular therapy.

Swimming bacteria move through a fluid by actuating their moving body parts. They are force-free and can be described as hydrodynamic force dipoles: pushers or pullers. This modelling description is broadly used in biological physics and active matter research, and it has successfully predicted, for example, the superfluid behaviour of suspensions of pushers or the bend instability and emergence of turbulent flows in active nematics. However, this description accounts only for the translational motion of the swimming body and neglects the effects of hydrodynamic torque dipoles, which are relevant to bacteria with rotary motor-driven flagella, such as swimming Escherichia coli. Here we show that the torque dipole of confined swimming E. coli can power the persistent rotation of symmetric discs. The torque dipole leads to a traction force on the discs, an additive mechanism that is both contactless and independent of the orientation of the bacteria. Our results indicate that the torque dipole of swimming E. coli is notable in confined geometries, which is relevant to bacterial transport through porous materials, biofilms and the development of chiral fluids.

Purpose
Surface micropatterning is being explored as a strategy to mitigate thrombus formation and reduce long-term anticoagulation requirements in left ventricular assist devices (LVADs). This study investigated whether specific micro-topographies can modulate platelet deposition under LVAD supraphysiological wall shear stress (WSS) conditions.

Materials and Methods
A custom microfluidic platform was developed to generate a linear WSS gradient from 16 to 130 Pa. Microchannels were patterned with reverse cones and hemispheres in small (1–3 µm) and large (3–9 µm) sizes using two-photon polymerization and nanoimprinting. Human blood was perfused through the microchannels, and platelet deposition was quantified over time as the area coverage ratio (Aₚₗₜ/Aₜₒₜ) and area under the curve (AUC). Platelet detachment events were counted as an indicator of thrombus stability, and computational simulations supported the interpretation of local shear conditions.

Results
Consistent trends emerged, although no statistical differences were observed relative to flat controls. Aₚₗₜ/Aₜₒₜ increased with WSS for all surfaces. At 16 Pa, small and large cones reduced platelet adhesion by approximately 84 and 98%, respectively, compared to flat controls. At 49 Pa, the reduction was about 95% for small cones and 80% for large cones. Conical geometries also promoted platelet washout at higher WSS. Small hemispherical features showed more than 50% lower platelet adhesion than flat surfaces for WSS > 16 Pa, with limited thrombus growth.

Conclusion
Conical micropatterns may be most effective at limiting platelet adhesion at lower WSS, while small hemispheres may perform better at higher WSS. These trends suggest a surface–shear interaction that warrants further investigation for LVAD surface optimization.