Monitoring Lower Back Activity in Daily Life Using Small Unintrusive Sensors and Wearable Electronics in the Context of Rheumatic and Musculoskeletal Diseases.

Due to a sedentary lifestyle, the amount of people suffering from musculoskeletal back diseases has increased over the last few decades. To monitor and cure these disabilities, sensors able to monitor the patient for long-term measurement during daily life and able to provide real-time feedback are required. There are only a few wearable systems that are capable to acquire muscle activity (sEMG) and posture at the same time. Moreover, previously reported systems do not target back sensor and typically comprise bulky uncomfortable solutions. In this paper, we present a new wearable sensor network that is designed to measure muscle activity and posture specialized for back measurement. Special care was taken to propose a discrete and comfortable solution. The prototype only measures 3.1 mm in thickness on the spine, making this sensor system the thinnest and lightest one in the literature to our best knowledge. After testing, it was shown that the sensor system is able to acquire two surface electromyography signals concurrently, to gather acceleration and rotation speed from the patient's lower back, and to transmit data to a computer or a smartphone via serial communication or Bluetooth low energy for a few hours for later processing and analysis.

Novel implantable pressure and acceleration sensor for bladder monitoring.

OBJECTIVES: To test the hypothesis that an implantable sensing system containing accelerometers can detect small-scale autonomous movements, also termed micromotions, which might be relevant to bladder physiology. METHODS: We developed a 6-mm submucosal implant containing a pressure sensor (MS5637) and a triaxial accelerometer (BMA280). Sensor prototypes were tested by implantation in the bladders of Gottingen minipigs. Repeated awake voiding cystometry was carried out with air-charged catheters in a standard urodynamic set-up as comparators. We identified four phases of voiding similar to cystometry in other animal models based on submucosal pressure. Acceleration signals were separated by frequency characteristics to isolate linear acceleration from the baseline acceleration. The total linear acceleration was calculated by the root mean square of the three measurement axes. Acceleration activity during voiding was investigated to adjacent 1-s windows and was compared with the registered pressure. RESULTS: We observed a total of 19 consecutive voids in five measurement sessions. A good correlation (r > 0.75) was observed between submucosal and catheter pressure in 14 of 19 premicturition traces. The peak-to-peak interval between maximum total linear acceleration was correlated with the interval between submucosal voiding pressure peaks (r = 0.760, P < 0.001). The total linear acceleration was higher during voiding compared with pre- and postmicturition periods (start of voiding/phase 1). CONCLUSIONS: To the best of our knowledge, this is the first report of bladder wall acceleration, a novel metric that reflects bladder wall movement. Submucosal sensors containing accelerometers can measure bladder pressure and acceleration.

Novel Fabrication Process for Integration of Microwave Sensors in Microfluidic Channels.

This paper presents a novel fabrication process that allows integration of polydimethylsiloxane (PDMS)-based microfluidic channels and metal electrodes on a wafer with a micrometer-range alignment accuracy. This high level of alignment accuracy enables integration of microwave and microfluidic technologies, and furthermore accurate microwave dielectric characterization of biological liquids and chemical compounds on a nanoliter scale. The microfluidic interface between the pump feed lines and the fluidic channels was obtained using magnets fluidic connection. The tube-channel interference and the fluidic channel-wafer adhesion was evaluated, and up to a pressure of 700 mBar no leakage was observed. The developed manufacturing process was tested on a design of a microwave-microfluidic capacitive sensor. An interdigital capacitor (IDC) and a microfluidic channel were manufactured with an alignment accuracy of 2.5 µm. The manufactured IDC sensor was used to demonstrate microwave dielectric sensing on deionized water and saline solutions with concentrations of 0.1, 0.5, 1, and 2.5 M.

Digital Microfluidics for Single Bacteria Capture and Selective Retrieval Using Optical Tweezers.

When screening microbial populations or consortia for interesting cells, their selective retrieval for further study can be of great interest. To this end, traditional fluorescence activated cell sorting (FACS) and optical tweezers (OT) enabled methods have typically been used. However, the former, although allowing cell sorting, fails to track dynamic cell behavior, while the latter has been limited to complex channel-based microfluidic platforms. In this study, digital microfluidics (DMF) was integrated with OT for selective trapping, relocation, and further proliferation of single bacterial cells, while offering continuous imaging of cells to evaluate dynamic cell behavior. To enable this, magnetic beads coated with Salmonella Typhimurium-targeting antibodies were seeded in the microwell array of the DMF platform, and used to capture single cells of a fluorescent S. Typhimurium population. Next, OT were used to select a bead with a bacterium of interest, based on its fluorescent expression, and to relocate this bead to a different microwell on the same or different array. Using an agar patch affixed on top, the relocated bacterium was subsequently allowed to proliferate. Our OT-integrated DMF platform thus successfully enabled selective trapping, retrieval, relocation, and proliferation of bacteria of interest at single-cell level, thereby enabling their downstream analysis.

System for recording from multiple flexible polyimide neural probes in freely behaving animals.

OBJECTIVE: Long-term electrophysiological recordings of neural activity in freely behaving animals are indispensable to advance the understanding of complex brain function. It is a technical challenge to chronically monitor the detailed activity across multiple distributed brain regions in freely behaving animals over a period of months. Here we present a new implant for inserting multiple flexible polyimide probes into freely behaving rats for monitoring the brain activity over a long time period. APPROACH: This brain implant integrates multiple flexible probes in small micromanipulator devices that ensure free behaviour of the animal. The probes are micromachined and the positioning mechanism is 3D-printed using stereolithography. Each probe is lowered by a screw-driven shuttle and guided through an exit tip before penetrating the rat's brain. MAIN RESULTS: The brain implant consists of 16 individually lowerable flexible polyimide probes that contain 16 embedded electrodes adding up to a total of 256 recording channels. The total travel distance is 8 mm. The assembly time of the device was only one day. The electrode impedance values had a mean of 335 kΩ and sample standard deviation of 107 kΩ after gold plating, excluding outliers. SIGNIFICANCE: For the first time, hyperdrive-assisted insertion of flexible multichannel probes was demonstrated. Local field potentials and neuronal spiking activity from freely behaving rats were recorded over months.

Magnetic Cell Centrifuge Platform Performance Study with Different Microsieve Pore Geometries.

The detection and analysis of circulating tumor cells (CTCs) plays a crucial role in clinical practice. However, the heterogeneity and rarity of CTCs make their capture and separation from peripheral blood very difficult while maintaining their structural integrity and viability. We previously demonstrated the effectiveness of the Magnetic Cell Centrifuge Platform (MCCP), which combined the magnetic-labeling cell separation mechanism with the size-based method. In this paper, a comparison of the effectiveness of different microsieve pore geometries toward MCCP is demonstrated to improve the yield of the target cell capture. Firstly, models of a trapped cell with rectangular and circular pore geometries are presented to compare the contact force using finite element numerical simulations. The device performance is then evaluated with both constant pressure and constant flow rate experimental conditions. In addition, the efficient isolation of magnetically labeled Hela cells with red fluorescent proteins (target cells) from Hela cells with green fluorescent protein (background cells) is validated. The experimental results show that the circular sieves yield 97% purity of the target cells from the sample with a throughput of up to 2 µL/s and 66-fold sample enrichment. This finding will pave the way for the design of a higher efficient MCCP systems.

Wireless intravesical device for real-time bladder pressure measurement: Study of consecutive voiding in awake minipigs.

Traditional urodynamics have poor correlation with urological symptoms. Ambulatory urodynamics may improve this correlation but the need for a transurethral catheter and the time-consuming nature of this examination limits its use. Therefore, the objective of this study was to develop a wireless real-time bladder pressure measurement device for repeated and prolonged-term measurement of bladder behavior in awake pigs. The Bladder Pill is an intravesical device with a pressure microsensor and a 3-dimensional inductive coupling coil for energy supply. A corresponding external coil provides wireless power transmission and real-time communication of bladder pressure data. To test the correlation between the pressure data measured by the device and by standard methods, we compared static water column pressures with this device and water-filled urodynamic catheter systems. In vivo assessment of awake voiding by the pill was done by introducing the bladder pill into the bladder of Göttingen minipigs. An air-charged urodynamic catheter was introduced transurethrally as control for pressure measurements. The optimal physical configuration of the pill was investigated to maximize the containment in the bladder. We used two versions of external signal receivers (one waistband and one rectangular frame) to test the optimal external signal capture. Next to that, we performed short-term and medium-term comparative pressure studies. The in vitro static pressure measurement demonstrated a mean difference of less than 1 cm H2O between the methods. The optimal design of the pill for maximal retainment in the bladder proved to be a pigtail configuration. The bending of the device during bladder contractions caused offset of 2.7 +/- 1.4 cm H2O (mean +/- SD) on the pressure measurements. The rectangular frame performed signal capture during 5 consecutive voids with a good correlation of the pressure measurements. The device can be inserted through the urethra and is retrieved using string or endoscopic extraction. In conclusion, wireless long-term measurement of bladder pressure is demonstrated and yields comparable results to current available catheter methods of measurement in a pig model.

Resonating Shell: A Spherical-Omnidirectional Ultrasound Transducer for Underwater Sensor Networks.

This paper presents the design and fabrication process of a spherical-omnidirectional ultrasound transducer for underwater sensor network applications. The transducer is based on the vibration of two hemispheres with a thickness of 1 mm and an outer diameter of 10 mm, which are actuated by two piezoelectric ring elements. Since the ultrasound wave is generated by the vibration of the two hemispheres, a matching layer is not required. Silicon Carbide (SiC) is used as the material of the hemispherical shells of the transducer. The shells were fabricated by laser sintering as an additive manufacturing method, in which the hemispheres were built layer by layer from a powder bed. All manufactured transducers with an outer dimension of 10 × 14.2 mm and a center frequency of 155 kHz were measured in a water tank by a hydrophone or in mutual communication. The circumferential source level was measured to vary less than 5dB. The power consumption and the insertion loss of the transducer, ranging from 100 µ W to 2.4 mW and 21.2 dB, respectively, along with all other measurements, prove that the transducer can transmit and receive ultrasound waves omnidirectionally at tens of centimeters intervals with a decent power consumption and low actuation voltage.

Dextran as a Resorbable Coating Material for Flexible Neural Probes.

In the quest for chronically reliable and bio-tolerable brain interfaces there has been a steady evolution towards the use of highly flexible, polymer-based electrode arrays. The reduced mechanical mismatch between implant and brain tissue has shown to reduce the evoked immune response, which in turn has a positive effect on signal stability and noise. Unfortunately, the low stiffness of the implants also has practical repercussions, making surgical insertion extremely difficult. In this work we explore the use of dextran as a coating material that temporarily stiffens the implant, preventing buckling during insertion. The mechanical properties of dextran coated neural probes are characterized, as well as the different parameters which influence the dissolution rate. Tuning parameters, such as coating thickness and molecular weight of the used dextran, allows customization of the stiffness and dissolution time to precisely match the user's needs. Finally, the immunological response to the coated electrodes was analyzed by performing a histological examination after four months of in vivo testing. The results indicated that a very limited amount of glial scar tissue was formed. Neurons have also infiltrated the area that was initially occupied by the dissolving dextran coating. There was no noticeable drop in neuron density around the site of implantation, confirming the suitability of the coating as a temporary aid during implantation of highly flexible polymer-based neural probes.

Capacitive multi-electrode array with real-time electrode selection for unobtrusive ECG & BIOZ monitoring.

Capacitively-coupled ECG (ccECG) and bioimpedance (ccBIOZ) measurements are highly sensitive to motion artefacts. This limits their use in real-life situations. This work presents an array-based system for the simultaneous acquisition of ccECG and ccBIOZ, together with a quality-based electrode scanning approach for ccECG. This allows to increase the time coverage of contactless measurements in real-life situations and reduces the impact of artefacts. This solution was evaluated on a car seat and a mattress prototype. Results show the benefit of this combined array and algorithm approach: for every body position the algorithm was able to find more than one electrode combination providing high-quality ccECG. Night-long recordings were also performed, resulting in a mean time coverage of 72.5%.

Inertial sensors versus standard systems in gait analysis: a systematic review and meta-analysis.

INTRODUCTION: The increasing popularity of inertial sensors in clinical practice is not supported by precise information on their reliability or guidelines for their use in rehabilitation. The authors investigated the state of the literature concerning the use of inertial sensors for gait analysis in both healthy and pathological adults comparing traditional systems. Furthermore, trying to define directions for clinicians. EVIDENCE ACQUISITION: In accordance with the PRISMA statement, authors searched in PubMed, Web of Science and Scopus all paper published from January 1st, 2005 until December 31st, 2017. They included both healthy and pathological adults' subjects as population, wearable or inertial sensors used for gait analysis and compared with classical gait analysis performed in a Motion Lab as intervention and comparison, gait parameters as outcomes. Considering the methodological quality, authors focused on: sample; description of the study; type of gait analysis used for comparison; type of sensor; sensor placement on the body; gait task requested. EVIDENCE SYNTHESIS: From a total of 888 articles, 16 manuscripts were selected and 7 of them were considered for meta-analysis for different gait parameters. Demographic data, tested devices, reference systems, test procedures and outcomes were analyzed. CONCLUSIONS: Our results show a good agreement between inertial sensors and classical gait analysis for some gait parameters, supporting their use as a solution for capturing kinematic information over an extended space and time and even outside a laboratory in real-life conditions. Authors can support the use of portable inertial sensors for a practical gait analysis in clinical setting with good reliability. It will then be the experience of the clinician to direct the decision-making process.

Teflon-on-Glass Molding Enables High-Throughput Fabrication of Hydrophilic-in-Hydrophobic Microwells for Bead-Based Digital Bioassays.

In recent years, Teflon-on-glass microwells have been successfully implemented in bead-based digital bioassays for the sensitive detection of single target molecules. Their hydrophilic-in-hydrophobic (HIH) nature enables the isolation and analysis of individual beads, carrying the target molecules, which can be further manipulated accurately through optical tweezer (OT) setups. However, these Teflon HIH-microwell platforms are conventionally fabricated through a complex, time-consuming and labor-intensive dry lift-off procedure which involves a series of major steps, limiting the up-scaling potential of these platforms. Alternative Teflon-based microwell fabrication methods have been extensively explored in literature but they preclude the generation of hydrophobic wells with hydrophilic bottom, thereby hampering the bioassay performance. Here, we present a new Teflon-on-glass molding method for the high throughput fabrication of hydrophilic-in-hydrophobic (HIH) microwell arrays, able to empower bead-based digital bioassays. Microwells 2.95 µm in depth and 3.86 µm in diameter were obtained to host individual beads. In these microwell arrays, sealing of reagents was demonstrated with an efficiency of 100% and seeding of superparamagnetic beads was achieved with an efficiency of 99.6%. The proposed method requires half as many steps when compared to the traditional dry lift-off process, is freely scalable and has the potential to be implemented in different bead-based bioassay applications.

Sub-femtomolar detection of DNA and discrimination of mutant strands using microwell-array assisted digital enzyme-linked oligonucleotide assay.

Detection methods that do not rely on the amplification of DNA but can reach sensitivity, specificity and throughput of gold standard methods, such as qPCR, have been extensively explored in recent years. Here, we present a hydrophilic-in-hydrophobic (HIH)-microwell array platform that empowers a panel of different amplification-free DNA bioassays: digital enzyme-linked oligonucleotide assay (ELONA), ligation-assisted (LA) digital ELONA and so-called 'analog' bioassays. We developed all three bioassays by using magnetic beads for capturing DNA target, followed by hybridization of enzyme-labelled detection probes and sealing of the built complexes into the femtoliter HIH microwells to achieve the fluorescent readout of single DNA molecules. With the optimized digital ELONA bioassay, we successfully detected 97 and 200 nt-long ssDNA molecules down to 68 and 92 aM, respectively, demonstrating extremely high sensitivity of the bioassay and its flexibility towards targets of different lengths. Importantly, we also proved that the same bioassay concept was suited to detect substantially higher concentrations of ssDNA (up to picomolar levels) by quantifying the total fluorescent intensity rather than counting fluorescent events for digital quantification. Finally, we advanced this concept towards LA digital ELONA capable of differentiating wildtype strands from those carrying single-point mutations even when the former were constituting only 1% of the DNA mixture and were present at 2 fM concentration. In conclusion, the developed platform showed remarkably high sensitivity, specificity and versatility for amplification-free detection of DNA and as such can be valuable for numerous applications in medical diagnostics, gene analysis, food safety and environmental monitoring.

Surface Nanostructuring of Parylene-C Coatings for Blood Contacting Implants.

This paper investigates the effects on the blood compatibility of surface nanostructuring of Parylene-C coating. The proposed technique, based on the consecutive use of O2 and SF6 plasma, alters the surface roughness and enhances the intrinsic hydrophobicity of Parylene-C. The degree of hydrophobicity of the prepared surface can be precisely controlled by opportunely adjusting the plasma exposure times. Static contact angle measurements, performed on treated Parylene-C, showed a maximum contact angle of 158°. The nanostructured Parylene-C retained its hydrophobicity up to 45 days, when stored in a dry environment. Storing the samples in a body-mimicking solution caused the contact angle to progressively decrease. However, at the end of the measurement, the plasma treated surfaces still exhibited a higher hydrophobicity than the untreated counterparts. The proposed treatment improved the performance of the polymer as a water diffusion barrier in a body simulating environment. Modifying the nanotopography of the polymer influences the adsorption of different blood plasma proteins. The adsorption of albumin—a platelet adhesion inhibitor—and of fibrinogen—a platelet adhesion promoter—was studied by fluorescence microscopy. The adsorption capacity increased monotonically with increasing hydrophobicity for both studied proteins. The effect on albumin adsorption was considerably higher than on fibrinogen. Study of the proteins simultaneous adsorption showed that the albumin to fibrinogen adsorbed ratio increases with substrate hydrophobicity, suggesting lower thrombogenicity of the nanostructured surfaces. Animal experiments proved that the treated surfaces did not trigger any blood clot or thrombus formation when directly exposed to the arterial blood flow. The findings above, together with the exceptional mechanical and insulation properties of Parylene-C, support its use for packaging implants chronically exposed to the blood flow.

A foldable electrode array for 3D recording of deep-seated abnormal brain cavities.

OBJECTIVE: This study describes the design and microfabrication of a foldable thin-film neural implant and investigates its suitability for electrical recording of deep-lying brain cavity walls. APPROACH: A new type of foldable neural electrode array is presented, which can be inserted through a cannula. The microfabricated electrode is specifically designed for electrical recording of the cavity wall of thalamic lesions resulting from stroke. The proof-of-concept is demonstrated by measurements in rat brain cavities. On implantation, the electrode array unfolds in the brain cavity, contacting the cavity walls and allowing recording at multiple anatomical locations. A three-layer microfabrication process based on UV-lithography and Reactive Ion Etching is described. Electrochemical characterization of the electrode is performed in addition to an in vivo experiment in which the implantation procedure and the unfolding of the electrode are tested and visualized. MAIN RESULTS: Electrochemical characterization validated the suitability of the electrode for in vivo use. CT imaging confirmed the unfolding of the electrode in the brain cavity and analysis of recorded local field potentials showed the ability to record neural signals of biological origin. SIGNIFICANCE: The conducted research confirms that it is possible to record neural activity from the inside wall of brain cavities at various anatomical locations after a single implantation procedure. This opens up possibilities towards research of abnormal brain cavities and the clinical conditions associated with them, such as central post-stroke pain.

Evaluation of a Multichannel Non-Contact ECG System and Signal Quality Algorithms for Sleep Apnea Detection and Monitoring.

Sleep-related conditions require high-cost and low-comfort diagnosis at the hospital during one night or longer. To overcome this situation, this work aims to evaluate an unobtrusive monitoring technique for sleep apnea. This paper presents, for the first time, the evaluation of contactless capacitively-coupled electrocardiography (ccECG) signals for the extraction of sleep apnea features, together with a comparison of different signal quality indicators. A multichannel ccECG system is used to collect signals from 15 subjects in a sleep environment from different positions. Reference quality labels were assigned for every 30-s segment. Quality indicators were calculated, and their signal classification performance was evaluated. Features for the detection of sleep apnea were extracted from capacitive and reference signals. Sleep apnea features related to heart rate and heart rate variability achieved high similarity to the reference values, with p-values of 0.94 and 0.98, which is in line with the more than 95% beat-matching obtained. Features related to signal morphology presented lower similarity with the reference, although signal similarity metrics of correlation and coherence were relatively high. Quality-based automatic classification of the signals had a maximum accuracy of 91%. Best-performing quality indicators were based on template correlation and beat-detection. Results suggest that using unobtrusive cardiac signals for the automatic detection of sleep apnea can achieve similar performance as contact signals, and indicates clinical value of ccECG. Moreover, signal segments can automatically be classified by the proposed quality metrics as a pre-processing step. Including contactless respiration signals is likely to improve the performance and provide a complete unobtrusive cardiorespiratory monitoring solution; this is a promising alternative that will allow the screening of more patients with higher comfort, for a longer time, and at a reduced cost.

A fast and accurate Langmuir-type polymer microtensiometer.

A semi-flexible polymer microtensiometer for local surface pressure measurements of Langmuir monolayers is presented. The current device geometry and read-out method via image analysis result in a theoretical accuracy of ±0.02mN⋅m-1 for a dynamic range between 0 and 75mN⋅m-1. The tensiometer sensitivity and dynamic range are easily tunable as they are solely based on the tensiometer spring dimensions. Finite element simulations are used to determine the response time of 20ms for a subphase viscosity of 1mPa⋅s. A poroviscomechanical model of the sensor is composed and the subphase viscosity is shown to dominate the transient behavior. The tensiometer performance is verified in a Langmuir trough by applying rapid local surface pressure oscillations. A Wilhelmy plate is used as an independent measurement tool and the results of both techniques correlate well.

Time Multiplexed Active Neural Probe with 1356 Parallel Recording Sites.

We present a high electrode density and high channel count CMOS (complementary metal-oxide-semiconductor) active neural probe containing 1344 neuron sized recording pixels (20 µm × 20 µm) and 12 reference pixels (20 µm × 80 µm), densely packed on a 50 µm thick, 100 µm wide, and 8 mm long shank. The active electrodes or pixels consist of dedicated in-situ circuits for signal source amplification, which are directly located under each electrode. The probe supports the simultaneous recording of all 1356 electrodes with sufficient signal to noise ratio for typical neuroscience applications. For enhanced performance, further noise reduction can be achieved while using half of the electrodes (678). Both of these numbers considerably surpass the state-of-the art active neural probes in both electrode count and number of recording channels. The measured input referred noise in the action potential band is 12.4 µVrms, while using 678 electrodes, with just 3 µW power dissipation per pixel and 45 µW per read-out channel (including data transmission).

Packaging of implantable accelerometers to monitor epicardial and endocardial wall motion.

Acceleration signals, collected from the inner and the outer heart wall, offer a mean of assessing cardiac function during surgery. Accelerometric measurements can also provide detailed insights into myocardial motion during exploratory investigations. Two different implantable accelerometers to respectively record endocardial and epicardial vibrations, have been developed by packaging a commercially available capacitive transducer. The same coating materials have been deposited on the two devices to ensure biocompatibility of the implants: Parylene-C, medical epoxy and Polydimethylsiloxane (PDMS). The different position-specific requirements resulted in two very dissimilar sensor assemblies. The endocardial accelerometer, that measures accelerations from the inner surface of the heart during acute animal tests, is a 2 mm-radius hemisphere fixed on a polymethyl methacrylate (PMMA) rod to be inserted through the heart wall. The epicardial accelerometer, that monitors the motion of the outer surface of the heart, is a three-legged structure with a stretchable polytetrafluoroethylene (PTFE) reinforcement. This device can follow the continuous motion of the myocardium (the muscular tissue of the heart) during the cardiac cycle, without hindering its natural movement. Leakage currents lower than 1 µA have been measured during two weeks of continuous operation in saline. Both transducers have been used, during animal tests, to simultaneously record and compare acceleration signals from corresponding locations on the inner and the outer heart wall of a female sheep.

Single-Step Imprinting of Femtoliter Microwell Arrays Allows Digital Bioassays with Attomolar Limit of Detection.

Bead-based microwell array technology is growing as an ultrasensitive analysis tool as exemplified by the successful commercial applications from Illumina and Quanterix for nucleic acid analysis and ultrasensitive protein measurements, respectively. High-efficiency seeding of magnetic beads is key for these applications and is enhanced by hydrophilic-in-hydrophobic microwell arrays, which are unfortunately often expensive or labor-intensive to manufacture. Here, we demonstrate a new single-step manufacturing approach for imprinting cheap and disposable hydrophilic-in-hydrophobic microwell arrays suitable for digital bioassays. Imprinting of arrays with hydrophilic-in-hydrophobic microwells is made possible using an innovative surface energy replication approach by means of a hydrophobic thiol-ene polymer formulation. In this polymer, hydrophobic-moiety-containing monomers self-assemble at the hydrophobic surface of the imprinting stamp, which results in a hydrophobic replica surface after polymerization. After removing the stamp, microwells with hydrophobic walls and a hydrophilic bottom are obtained. We demonstrate that the hydrophilic-in-hydrophobic imprinted microwell arrays enable successful and efficient self-assembly of individual water droplets and seeding of magnetic beads with loading efficiencies up to 96%. We also demonstrate the suitability of the microwell arrays for the isolation and digital counting of single molecules achieving a limit of detection of 17.4 aM when performing a streptavidin-biotin binding assay as model system. Since this approach is up-scalable through reaction injection molding, we expect it will contribute substantially to the translation of ultrasensitive digital microwell array technology toward diagnostic applications.