Minimally invasive surgery has transformed patient recovery, but it has robbed surgeons of a fundamental sense: touch. Now, researchers at NYU Abu Dhabi have developed soft, flexible microfluidic force sensors that restore real-time tactile feedback during keyhole procedures, according to a study published in Microsystems & Nanoengineering. The work could mark a turning point in the design of smarter, safer surgical instruments.
minimally invasive procedures.
Laparoscopic surgery offers patients faster recovery, less post-operative pain, and reduced risk of infection compared with open procedures. Yet the long, rigid instruments threaded through small incisions impose a significant clinical trade-off: surgeons lose the ability to feel the resistance and texture of the tissue they are manipulating. Grip too firmly, and delicate structures tear; grip too lightly, and control is lost. For decades, this sensory deficit has been one of minimally invasive surgery’s most stubborn limitations.
Tactile sensing is far from a niche engineering concern. In robotics, wearable electronics, and medical instrumentation, the ability to perceive and respond to physical interactions with the environment underpins feedback control, object manipulation, and real-time decision-making. In surgery, the stakes are particularly high. Conventional force sensors have traditionally relied on rigid solid-state technologies
– including Micro-Electro-Mechanical Systems (MEMS) – which offer excellent sensitivity and compact form factors but are fundamentally ill-suited to the compliant, curved, and dynamic surfaces of surgical instruments. Their mechanical rigidity creates a mismatch that can compromise both performance and safety.
A team led by Associate Professor Mohammad A. Qasaimeh at NYU Abu Dhabi’s Engineering Division has now developed a practical solution. Their multichannel soft microfluidic force sensors – fabricated from polydimethylsiloxane (PDMS) and filled with Galinstan, a biocompatible eutectic liquid metal alloy of gallium, indium, and tin – can measure forces ranging from the gentlest tissue contact to forceful grasping, all in real time. The findings were published in Microsystems & Nanoengineering on 20 April 2026.
“Minimally invasive surgery benefits patients, but it also removes a key human capability: the surgeon’s sense of touch,” said Qasaimeh. “In this work, we developed soft sensors that can capture a wide range of forces while remaining easy to integrate with existing tools, moving us closer to smarter and safer surgical instruments.”
How the sensors work
The sensing mechanism is elegantly straightforward. When a normal force is applied to the PDMS structure, the elastomer deforms, compressing the Galinstanfilled microchannels embedded within it. This reduces the channel’s cross-sectional area, increasing its electrical resistance in a measurable, calibrated way. The greater the force, the greater the resistance change – a relationship that can be precisely quantified using the standard resistivity equation governing the electrical behaviour of the liquid metal within the channel.
Galinstan was selected as the active sensing element for good reason. At room temperature it exhibits a dynamic viscosity of approximately 2.4 mPa·s, high electrical conductivity, low melting temperature, non-toxicity, and ultralow vapour pressure. Unlike mercury, it is safe for biomedical applications. Combined with PDMS – chosen for its high elasticity, tunable stiffness, optical transparency, and biocompatibility – the two materials form a robust platform for soft, stretchable force sensing.
The team systematically evaluated how key design parameters affect sensitivity and working range, using both finite element analysis (FEA) simulations in COMSOL Multiphysics and experimental validation. Among the variables assessed were microchannel cross-sectional geometry, vertical depth of the microchannel within the sensor, sensor thickness, and the stiffness of the PDMS elastomer – controlled by varying the base-to-crosslinker mixing ratio and curing duration.
Among the geometries tested – including spiral, flower-inspired, and strain gauge-inspired layouts – an inverted stepped-triangle microchannel cross-section consistently delivered the highest sensitivity. Thinner sensors and softer PDMS formulations also enhanced responsiveness, consistent with Hooke’s law of elasticity. Shallower microchannels, positioned closer to the sensor surface, were more prone to force-induced deformation and therefore more sensitive to applied loads.
Crucially, the entire fabrication process requires no cleanroom. Mould designs were produced using desktop digital light processing (DLP) 3D printing with Plas-CLEAR resin, followed by PDMS casting and Galinstan injection via vacuum-assisted filling. By incorporating injection inlets and electrical terminal channels directly into the mould design, the team eliminated common manual post-processing steps, improving yield and simplifying assembly. The result is a reproducible, low-cost fabrication protocol accessible to standard research laboratories – an important consideration for eventual clinical translation and the prototyping of single-use disposable sensors.
Multichannel designs extend sensing range
A particularly significant contribution of the study is the development of multichannel sensor architectures that extend the dynamic range of force detection within a single compact device. Two principal approaches were explored.
The first involved multilayer designs, in which two spiral microchannels were positioned at different vertical depths within a stacked PDMS structure. The upper microchannel, closer to the surface, experienced greater deformation under load and provided higher sensitivity at low forces; the lower microchannel, further from the surface, underwent less deformation and offered an extended linear working range at higher forces. The two channels thus operated in complementary fashion, together spanning a broader force range than either could achieve alone.
The second approach used coplanar multichannel configurations, embedding multiple microchannels with different geometries or cross-sectional dimensions within a single PDMS layer. Flower-inspired designs incorporated two concentric microchannels arranged in petal-like patterns, whilst strain gauge-inspired designs placed two serpentine microchannels side by side with differing aspect ratios. In both cases, the channels exhibited distinct force-response profiles, enabling dual-range sensing without the additional fabrication complexity of multilayer bonding.
First author Wael Othman, formerly a postdoctoral associate at NYU Abu Dhabi and now Assistant Professor at Khalifa University, described the rationale: “Our goal was to create sensors that are both sensitive and practical for real surgical environments. This design allows us to measure both gentle and strong forces within the same small device, and to place sensors where they are most useful on surgical tools.”
A dual-sensor system for the operating theatre
To demonstrate clinical applicability, the researchers integrated two single-channel sensors onto a standard laparoscopic grasper. A teeth-patterned strain gauge sensor – designed to mimic the gripping surface of a conventional metallic grasper jaw, and incorporating the inverted stepped-triangle microchannel geometry identified as the most sensitive – was mounted on one jaw to capture tissue contact forces. A spiral sensor was placed on the thumb ring of the handle to measure the actuation force applied by the surgeon during jaw manipulation.
The choice of sensor placement also has practical implications for sterilisation and ease of use. Mounting the handle sensor off the jaw keeps the instrument tip unobstructed and easier to sterilise, whilst jaw-mounted sensors provide more direct measurement of tool-tissue interaction forces – a flexibility the authors highlight as an advantage of the platform’s modular design.
During testing with cylindrical PDMS tissue phantoms, the jaw sensor reliably captured grasp-and-release force cycles in real time, whilst the handle sensor simultaneously tracked the surgeon’s thumb actuation forces. Fabrication reproducibility was strong, with output signal variation across identically produced sensors remaining within ±5%. Dynamic response testing demonstrated a response time of 65 ms and a recovery time of 80 ms – performance characteristics consistent with the demands of real surgical manipulation.
The authors note that this dual-sensor configuration “establishes a multimodal tactile feedback system that effectively restores a sense of ‘touch’ in MIS tools, facilitating safer and more informed tissue manipulation.” Previous work by the same group has validated a strong correlation between forces measured at the handle and those applied at the jaws, meaning that even the off-jaw handle sensor can be used to reconstruct tissue contact forces during grasping events.
Limitations and future directions
Long-term storage testing over 16 months highlighted one area requiring attention: gradual stiffening of the PDMS due to natural ageing increased sensor stiffness and altered the force-response signal over time. The authors recommend routine calibration for sensors intended for extended use – a practical consideration that will need to be addressed in any pathway towards clinical deployment.
Future work will focus on improving simulation accuracy through nonlinear PDMS material models and mesh refinement near the microchannel-substrate interface. The team also intends to integrate the sensors with wireless microcontrollers for portable, real-time data acquisition, and to explore multimodal sensing of shear stresses, torque, and bending.
The broader implications extend well beyond laparoscopy. As the authors conclude, the platform “provides a foundation for developing next-generation soft sensors for biomedical instrumentation, soft robotics, and human-machine interfaces” – with potential applications in surgical training, robotic automation, and intraoperative decision support.
Reference:
Othman, W., Qasaimeh, M. A., et al. (2026). Multichannel soft microfluidic force sensors: design, characterization, and application in laparoscopy. Microsystems & Nanoengineering, 12, 138. https://doi.org/10.1038/s41378-026-01263-8
