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Nuclear morphology plays a critical role in regulating gene expression and cell functions. While most research has focused on the direct effects of nuclear morphology on cell fate, its impact on the cell secretome and surrounding cells remains largely unexplored. In this study, we fabricate implants with a micropillar topography using methacrylated poly(octamethylene citrate)/hydroxyapatite (mPOC/HA) composites to investigate how micropillar-induced nuclear deformation influences cell secretome for osteogenesis and cranial bone regeneration. In vitro, cells with deformed nuclei show enhanced secretion of proteins that support extracellular matrix (ECM) organization, which promotes osteogenic differentiation in neighboring mesenchymal stromal cells (MSCs). In a female mouse model with critical-size cranial defects, nuclear-deformed MSCs on micropillar mPOC/HA implants elevate Col1a2 expression, contributing to bone matrix formation, and drive cell differentiation toward osteogenic progenitor cells. These findings indicate that micropillars modulate the secretome of hMSCs, thereby influencing the fate of surrounding cells through matricrine effects. 

Reverse electrowetting-on-dielectric (REWOD) energy harvesting is an effective energy harvesting method at low frequencies such as the frequencies of human motion. Various REWOD energy harvester designs have been presented in prior works, but these generally use rigid and often expensive substrates and time-consuming and/or costly fabrication methods. To address these challenges, in this work REWOD energy harvesters were fabricated consisting of aluminized polyester sheets as the functional layers and with polycarbonate sheets for added mechanical support. The fabrication of these samples eliminates the need for costly materials, clean room technologies, and high-end equipment. Samples were characterized using a flat arrangement and on a test fixture that simulates the repeated bending that occurs on the back of a bending knee. Without applying any external bias voltage, the maximum voltage and current output for the bending samples were determined to be 25.1 mV and 230 nA, respectively, and the corresponding maximum power is 5.77 nW at a bending frequency of 5 Hz. With an estimated cost of U.S. $ 0.28 for each REWOD harvester (U.S. $ 0.03/cm2), the cost per nanowatt of power is U.S. $ 0.05/nW, which is approximately 380 times lower than the approximately U.S. $ 19/nW of our previous REWOD energy harvesters. Our simple devices provide a low-cost, easily fabricated flexible approach to wearable motion sensing and energy harvesting that can be useful for various healthcare applications. 

A unique method for capturing energy from mechanical electrolyte modulation is known as reverse electrowetting-on-dielectric (REWOD). Prior REWOD studies relied on rigid electrodes which demand a high bias voltage to maximize harvested power, hindering the advancement of self-powered wearable health-monitoring sensors. In addition, the amount of energy harvested via the REWOD technique can be improved to a greater extent with the utilization of a high-dielectric (high-k) metal oxide (HDMO) layer on flexible electrodes. In this study, two distinct sets of electrodes that are flexible are utilized for harvesting energy with the REWOD phenomenon. The samples were coated with HDMO layers, namely, hafnium oxide (HfO2) and manganese dioxide (MnO2), respectively. The material deposition on a polyimide sheet is employed via a sputtering-based physical vapor deposition (PVD). The utilization of MnO2 samples with the proposed flexing REWOD test measurement generated 476.21 μW/cm2 an utmost power density value with an encapsulated electrolyte between electrodes. 

Abstract This paper presents a motion-sensing device with the capability of harvesting energy from low-frequency motion activities. Based on the high surface area reverse electrowetting-on-dielectric (REWOD) energy harvesting technique, mechanical modulation of the liquid generates an AC signal, which is modeled analytically and implemented in Matlab and COMSOL. A constant DC voltage is produced by using a rectifier and a DC–DC converter to power up the motion-sensing read-out circuit. A charge amplifier converts the generated charge into a proportional output voltage, which is transmitted wirelessly to a remote receiver. The harvested DC voltage after the rectifier and DC–DC converter is found to be 3.3 V, having a measured power conversion efficiency (PCE) of the rectifier as high as 40.26% at 5 Hz frequency. The energy harvester demonstrates a linear relationship between the frequency of motion and the generated output power, making it highly suitable as a self-powered wearable motion sensor.