Ismail Emre Araci

Soft, skin-conformal fluidic systems are essential for wearable healthcare; however, micropumps that rely on rigid external hardware for actuation have limited portability and on-body integration. Here, we introduce OSMiPump, a power-free, strain-driven micropump that directly converts natural human motion into unidirectional fluid transport using a soft, monolithic architecture. OSMiPump integrates out-of-surface microchannels (OSMiCs) with self-actuated valves (OSMiValves), where cyclic tensile strain induces volume reduction and valve snap-through/snap-back, producing reliable directionality over repeated strain cycles. Computational fluid-structure interaction modeling and nonlinear shell deformation analysis validate the operating mechanism. Experimentally, OSMiPump exhibits predictable performance across valve geometries, strain levels and profiles, fluid viscosities, and inlet/outlet resistance configurations. At 20% strain, it achieves average flow rates up to ~0.16 µL/s under low-resistance conditions and maintains ~0.02 µL/s under high-resistance conditions, reaching peak pressures of ~11 kPa and sustaining an average pressure of ~0.6 kPa, with consistent operation over 100 cycles. The self-morphing architecture further enables tunable pumping behavior, including adjustable strain thresholds and response dynamics. Wearable demonstrations show direct actuation by body motion and enable both on-body delivery and removal for applications such as wound care and drug administration during physical rehabilitation, exercise, or daily activities. Integration into silicone socks and skin-mounted Tegaderm films illustrates the versatility of the platform. Together, these results establish OSMiPump as a soft, monolithic, and skin-conformal micropump for next-generation wearable biomedical systems. The alternative text for this image may have been generated using AI.

The volume of natural materials increases under tension, thus conventionally biomechanical actuation of fluidic pumps relies on compression for pressure generation. Here, we report on out-of-surface microchannels (OSMiCs) that exhibit negative volumetric strain (i.e., pressure generation) under skin-induced tensile strain. Monolithic polydimethylsiloxane (PDMS) patches were fabricated and characterized. The complex relations between the wrinkling and buckling of the OSMiC shell and the fluid flow patterns were investigated. OSMiCs were shown to snap-back (-through) between two stable states that lead to (ir)reversible fluid flow depending on their architecture. Unlike standard microchannels that only generate pressure symmetrically upon application and release of tensile strain, OSMiCs are shown to be tunable for providing an asymmetrical pressure owing to their shape-change property (i.e., morphing). The maximum forward (backward) flow pressure of 10 (−14) kPa was measured upon 20% uniaxial strain application (release). The versatile fabrication technique allowed the integration of OSMiCs with different Q values, leading to a discrete strain-actuated flow control element. Numerical simulations were conducted and shown to support the experimentally observed wrinkling and buckling behavior. Finally, the operation of the power-free OSMiC skin patch for strain-based liquid administration on skin was demonstrated.

The capability to record data in passive, image-based wearable sensors can simplify data readouts and eliminate the requirement for the integration of electronic components on the skin. Here, we developed a skin-strain-actuated microfluidic pump (SAMP) that utilizes asymmetric aspect ratio channels for the recording of human activity in the fluidic domain. An analytical model describing the SAMP’s operation mechanism as a wearable microfluidic device was established. Fabrication of the SAMP was achieved using soft lithography from polydimethylsiloxane (PDMS). Benchtop experimental results and theoretical predictions were shown to be in good agreement. The SAMP was mounted on human skin and experiments conducted on volunteer subjects demonstrated the SAMP’s capability to record human activity for hundreds of cycles in the fluidic domain through the observation of a stable liquid meniscus. Proof-of-concept experiments further revealed that the SAMP could quantify a single wrist activity repetition or distinguish between three different shoulder activities.

Control channels on microfluidic large-scale integration (mLSI) chips are prone to blockage and leakage defects. In this work, we propose a built-in self-test (BIST) method that drastically improves the test efficiency. Given n to-be-tested control channels, we reduced the number of test patterns for blockage and leakage tests from [EQUATION] to 1, and from ⌈log₂(n + 1)⌉ to ⌈log₂(χ^{(G) + 1)}⌉, respectively, where χ(G) denotes the vertex chromatic number of a graph G consisting of n vertices. We fabricated our design and demonstrated the feasibility and efficiency of our method.

After decades of development, flow-based microfluidic biochips have become an increasingly attractive platform for biochemical experiments. The fluid transportation and the on-chip device operation are controlled by microvalves, which are driven by external pneumatic controllers. To meet the increasingly complex experimental demands, the number of microvalves has significantly increased, making it necessary to adopt multiplexers (MUXes) for the actuation of microvalves. However, existing MUX designs have limited coding capacities, resulting in area overhead and excessive chip-to-world interface. This paper proposes a novel gate structure for modifying the current MUX architecture, along with a mixed coding strategy that achieves the maximum coding capacity within the modified MUX architecture. Additionally, an efficient synthesis tool for the mixed-coding-based MUXes (LaMUXes) is presented. Experimental results demonstrate that the LaMUX is exceptionally efficient, substantially reducing the usage of pneumatic controllers and microvalves compared to existing MUX designs.

Skin-strain-field is used as a fingerprint of the human movement to guide the design of an integrated strain sensor for digital human motion recognition.

Microinjection is an essential process in genetic engineering that is used to deliver genetic materials into various biological specimens. Considering the high-throughput requirement for microinjection applications ranging from gene editing to cell therapies, there is a need for an automated, highly parallelized, reproducible, and easy-to-use microinjection strategy. Here we report an on-chip, microfluidic microinjection module designed for compatibility with microfluidic large-scale integration technology that can be fabricated via standard, multilayer soft lithography techniques. The needle-on-chip (NOC) module consists of a two-layer polydimethylsiloxane-based microfluidic module whose puncture and injection operations are reliant solely on Quake valve actuation. As a proof-of-concept, we designed a NOC module to conduct the microinjection of a common genetics model organism, Caenorhabditis elegans ( C. elegans ). The NOC design was analyzed using finite element method simulations for a large range of practically viable geometrical parameters. The computational results suggested that a slight lateral offset (>10 μ m) of the control channel is sufficient for a successful NOC operation with a large fabrication tolerance (50 μ m, 50% channel width). To demonstrate proof-of-concept, the microinjection platform was fabricated and utilized to perform a successful injection of a tracer dye into C. elegans .

Microfluidic large-scale integration (mLSI) is a promising lab-on-a-chip platform for high-throughput bio-applications. Due to the high integration scale and the small feature size, control channels on mLSI chips are prone to blockage and leakage defects, which may lead to faulty behavior of valves and erroneous experimental results. Thus, mLSI chips need to be tested before usage. Current mLSI-tests are mostly performed in a straightforward way by testing each valve individually, which is very time-consuming and error-prone. As the integration scale of mLSI chips keeps increasing, there is a pressing demand for more efficient test approaches. This work proposes the first built-in-self-test (BIST) method for mLSI with an integrated test module design. Instead of testing individual valves, the proposed method directly tests the control channels and thus greatly improves the test efficiency. Only n2 and log2(n+1)test operations are required to test the blockage and leakage defects, respectively, of n control channels. The proposed test module consumes moderate area overhead and the test method is easy to operate. Neither specialized software nor external pressure sensors are required for carrying out the tests. Experiments show that our test approach is sensitive enough to detect defects that have a feature size as small as 10μm and that are several centimeters away from the test module.

Microfluidic devices filled with conductive liquids exhibit a unique potential to integrate fluid physics and electronics while maintaining low mechanical load (i.e., extremely soft and stretchable) for skin mounted wearable device applications. Here, a novel microfluidic strain sensing mechanism is presented, which provides a theoretically unlimited tunable gauge factor, directionally specific and linear response, and negligible hysteresis for skin deformation measurements. The control over flow dynamics enables signal filtering, thresholding, and basic logic operations to be performed in the fluidic‐domain potentially simplifying the electronic and digital processing components. The capillaric strain sensor technology relies on the ultrahigh electrical resistance modification due to the capillary flow of conductive ionic liquids in response to the elastomeric deformation of silicone microchannels. The directional specificity and ultrahigh sensitivity (e.g., gauge factor > 3000) are demonstrated for distinguishing facial activity types and the subtle differences in facial muscle‐strengthening activities.

Locomotion at low Reynolds numbers encounters stringent physical constraints due to the dominance of viscous over inertial forces. A variety of swimming microorganisms have demonstrated diverse strategies to generate self-propulsion in the absence of inertia. In particular, ameboid and euglenoid movements exploit shape deformations of the cell body for locomotion. Inspired by these biological organisms, the ‘push-me-pull-you’ (PMPY) swimmer (Avron J E et al 2005 New J. Phys. 7 234) represents an elegant artificial swimmer that can escape from the constraints of the scallop theorem and generate self-propulsion in highly viscous fluid environments. In this work, we present the first experimental realization of the PMPY swimmer, which consists of a pair of expandable spheres connected by an extensible link. We designed and constructed robotic PMPY swimmers and characterized their propulsion performance in highly viscous silicone oil in dynamically similar, macroscopic experiments. The proof-of-concept demonstrates the feasibility and robustness of the PMPY mechanism as a viable locomotion strategy at low Reynolds numbers.