Three-dimensional Microdevices Research Articles

Integrated Three-Dimensional Microdevice with a Modified Surface for Enhanced DNA Separation from Biological Samples.

Functional interfaces and devices for rapid adsorption and immobilization of nucleic acids (NAs) are significant for relevant bioengineering applications. Herein, a microdevice with poly(acrylic acid) (PAA) photosensitive resin was integrated by three-dimensional (3D) printing, named DPAA for short. Precise microscale structures and abundant surface carboxyl functional groups were fabricated for fast and high-throughput deoxyribonucleic acid (DNA) separation. Surface modification was then done using polydopamine (PDA) and poly(ethylene glycol) (PEG) to obtain modified poly(acrylic acid) (PAA)-based devices DPDA-PAA and DPEG-PAA rich in amino and hydroxyl groups, respectively. The fabricated device DPAA possessed superior printing accuracy (40-50 μm). Functionalization of amino and hydroxyl was successful, and the modified devices DPDA-PAA and DPEG-PAA maintained a high thermal stability like DPAA. Surface potential analysis and molecular dynamics simulation indicated that the affinity for DNA was in the order of DPDA-PAA > DPEG-PAA > DPAA. Further DNA separation experiments confirmed the high throughput and high selectivity of DNA separation performance, consistent with the predicted affinity results. DPDA-PAA showed relatively the highest DNA extraction yield, while DPEG-PAA was the worst. An acidic binding system is more favorable for DNA separation and recovery. DPDA-PAA showed significantly better DNA extraction performance than DPAA in a weakly acidic environment (pH 5.0-7.0), and the average DNA yield of the first elution was 2.16 times that of DPAA. This work validates the possibility of modification on integrated 3D microdevices to improve their DNA separation efficiency effectively. It also provides a new direction for the rational design and functionalization of bioengineering separators based on nonmagnetic methods. It may pave a new path for the highly efficient polymerase chain reaction diagnosis.

Bioethical implications of organ-on-a-chip on modernizing drug development.

Organ-on-chips are three-dimensional microdevices that emulate the structure, functionality, and behavior of specific tissues or organs using human cells. Combining organoids with microfabricated fluidic channels and microelectronics, these systems offer a promising platform for studying disease mechanisms, drug responses, and tissue performance. By replicating the in vivo microenvironment, these devices can recreate complex cell interactions in controlled conditions and facilitate research in various fields, including drug toxicity and efficacy studies, biochemical analysis, and disease pathogenesis. Integrating human induced pluripotent stem cells further enhances their applicability, thereby enabling patient-specific disease modeling for precision medicine. Although challenges like economy-of-scale, multichip integration, and regulatory compliance exist, advances in this modular technology show promise for lowering drug development costs, improving reproducibility, and reducing the reliance on animal testing. The ethical landscape surrounding organ-on-chip usage presents both benefits and concerns. While these chips offer an alternative to animal testing and potential cost savings, they raise ethical considerations related to community engagement, informed consent, and the need for standardized guidelines. Ensuring public acceptance and involvement in decision-making is vital to address misinformation and mistrust. Furthermore, personalized medicine models using patient-derived cells demand careful consideration of potential ethical dilemmas, such as modeling physiological functions of fetuses or brains and determining the extent of protection for these models. To achieve the full potential of organ-on-a-chip models, collaboration between scientists, ethicists, and regulators is essential to fulfil the promise of transforming drug development, advancing personalized medicine, and contributing to a more ethical and efficient biomedical research landscape.

Applications of Light-Sheet Microscopy in Microdevices.

Light-sheet fluorescence microscopy (LSFM) has been present in cell biology laboratories for quite some time, mainly as custom-made systems, with imaging applications ranging from single cells (in the micrometer scale) to small organisms (in the millimeter scale). Such microscopes distinguish themselves for having very low phototoxicity levels and high spatial and temporal resolution, properties that make them ideal for a large range of applications. These include the study of cellular dynamics, in particular cellular motion which is essential to processes such as tumor metastasis and tissue development. Experimental setups make extensive use of microdevices (bioMEMS) that provide better control over the substrate environment than traditional cell culture experiments. For example, to mimic in vivo conditions, experiment biochemical dynamics, and trap, move or count cells. Microdevices provide a higher degree of empirical complexity but, so far, most have been designed to be imaged through wide-field or confocal microscopes. Nonetheless, the properties of LSFM render it ideal for 3D characterization of active cells. When working with microdevices, confocal microscopy is more widespread than LSFM even though it suffers from higher phototoxicity and slower acquisition speeds. It is sometimes possible to illuminate with a light-sheet microdevices designed for confocal microscopes. However, these bioMEMS must be redesigned to exploit the full potential of LSFM and image more frequently on a wider scale phenomena such as motion, traction, differentiation, and diffusion of molecules. The use of microdevices for LSFM has extended beyond cell tracking studies into experiments regarding cytometry, spheroid cultures and lab-on-a-chip automation. Due to light-sheet microscopy being in its early stages, a setup of these characteristics demands some degree of optical expertise; and designing three-dimensional microdevices requires facilities, ingenuity, and experience in microfabrication. In this paper, we explore different approaches where light-sheet microscopy can achieve single-cell and subcellular resolution within microdevices, and provide a few pointers on how these experiments may be improved.

Two-Photon Nanolithography of Tailored Hollow three-dimensional Microdevices for Biosystems

Functional three-dimensional (3D) microstructures incorporating accessible interiors have emerged as a versatile platform for biosystem applications. By configuring their 3D geometric features, these biosystem microdevices can accurately evaluate and control targeted bioenvironments. However, classical fabrication techniques based on photolithography-etching processes cannot precisely and programmably control the geometric of the entire hollow 3D microstructures. Here, we proposed the use of a two-photon polymerization (TPP)-based technique for the precise, straightforward, and customizable preparation of hollow 3D microstructure devices with small opening(s). Factors governing the formation of hollow 3D biosystem microdevices, including material composition, laser input, and (post-) development treatment, have been systematically investigated and a set of optimized conditions are presented as a starting point for the development of novel hollow biosystem microdevices. To evaluate the broad applicability of this approach, a series of tailored hollow 3D microdevices with small opening(s), including a micropore, microneedle, microelectrode, microvalve, and micromachine, were successfully prepared using our direct laser writing-TPP technique. To further validate the feasibility of these biosystem microdevices in practical implementations, we demonstrated the use of hollow 3D micropore devices for the robust resistive-pulse analysis of nanoparticles.

3D microdevices that perform sample purification and multiplex qRT-PCR for early cancer detection with confirmation of specific RNAs

MicroRNA expression analysis is an important screening tool for the early detection of cancer. In this study, we developed two portable three-dimensional microdevices for multiple singleplex RNA expression analysis by microRNA purification and qRT-PCR as a prototype for point-of-care testing. These microdevices are composed of several types of modules termed ‘chemical IC chips’. We successfully reduced the heating area and fluorescence observation area, reduced the energy required for the reaction, and improved the portability of all systems in the devices. The purification microdevice could purify the microRNA from the sample using the FTA elute card system. The disposable reactor module mounted on both devices was easily fabricated by deforming a 100-μm-thick polypropylene film using an uncomplicated procedure. The qRT-PCR microdevice could perform reactions for samples of small volume. We purified microRNA from the HepG2 liver cancer cell line using the purification microdevice and confirmed the expression level of miR-224, which is a potential biomarker for liver cancer. Furthermore, we observed an increase in the fluorescence intensity when we performed qRT-PCR in the qRT-PCR microdevice. Therefore, the two developed microdevices show promise as a new portable tool for early cancer detection.

Induction of epithelial-to-mesenchymal transition in proximal tubular epithelial cells on microfluidic devices

In proteinuric nephropathy, epithelial-to-mesenchymal transition (EMT) is an important mechanism that causes renal interstitial fibrosis. The precise role of EMT in the pathogenesis of fibrosis remains controversial, partly due to the absence of suitable in vitro or in vivo models. We developed two microfluidic and compartmental chips that reproduced the fluidic and three-dimensional microenvironment of proximal tubular epithelial cells in vivo. Using one microfluidic device, we stimulated epithelial cells with a flow of healthy human serum, heat-inactivated serum and complement C3a, which mimicked the flow of urine within the proximal tubule. We observed that epithelial cells exposed to serum proteins became apoptotic or developed a mesenchymal phenotype. Incubating cells with C3a induced similar features. However, cells exposed to heat-inactivated serum did not adopt the mesenchymal phenotype. Furthermore, we successfully recorded the cellular morphological changes and the process of transmigration into basement membrane extract during EMT in real-time using another three-dimensional microdevice. In conclusion, we have established a cell-culture system that mimics the native microenvironment of the proximal tubule to a certain extent. Our data indicates that EMT did occur in epithelial cells that were exposed to serum proteins, and C3a plays an essential role in this pathological process.

5-Fluorouracil delivery from a novel three-dimensional micro-device: in vitro and in vivo evaluation

A novel three-dimensional biodegradable micro-device using microelectromechanical systems technology was developed for implantable controlled drug delivery. In order to evaluate the effect of monomer composition and molecular weight of poly(lactic-co-glycolic acid) (PLGA) on the drug release, three 5-Fluorouracil loaded micro-devices, made of 50/50, 27kDa; 50/50, 40kDa and 75/25 27kDa PLGA, were prepared and characterized by in vitro and in vivo methods. The in vitro drug release from three micro-devices followed zero-order kinetics, and PLGA micro-device with the higher molecular weight and lactide/glycolide ratio tended to a longer sustained release period. The in vivo release results agreed with the in vitro results and drug release in vivo was faster than that in vitro for each of micro-devices. And three micro-devices showed different tumor inhibition effect in the tumor bearing mice. In addition, the SEM and weight loss experiments showed that PLGA micro-devices with lower molecular weight and lactide/glycolide ratio had faster degradation. These data provided the information for the optimization of the novel three-dimensional biodegradable micro-device to obtain more suitable systems for controlled release and to meet release requirements of different drugs.

Photoresist Spray Coating Using a Shield Plate with an Aperture for Uniform Deposition onto Trench-Type Three-Dimensional Microdevice Structures

The spray coating of a photoresist using a shield plate with an aperture is carried out for uniform deposition onto three-dimensional (3D) trench structures. The shield plate set over a sample blocks resist deposition onto the sample, except in the aperture area. Numerical analysis reveals that the vertical velocity component of gas flow is enhanced in the aperture area. In experiments on spray coating, the difference between the thicknesses of resist films deposited on top and bottom trench surfaces is decreased. On the trench sidewall, resist bump formation, which is frequently observed in spray coating, is suppressed. The profile of the resist film becomes conformal and uniform. Such resist deposition is necessary to realize 3D microdevices. In microfluidic devices using dielectrophoresis, aside from the top and bottom trench surfaces, the trench sidewall can be used for preparing device structures such as electrode. Electric interaction is enhanced for controlling the transport of micro-/nano-scale objects in micro-trench structures.

Photoresist Spray Coating Using a Shield Plate with an Aperture for Uniform Deposition onto Trench-Type Three-Dimensional Microdevice Structures

The spray coating of a photoresist using a shield plate with an aperture is carried out for uniform deposition onto three-dimensional (3D) trench structures. The shield plate set over a sample blocks resist deposition onto the sample, except in the aperture area. Numerical analysis reveals that the vertical velocity component of gas flow is enhanced in the aperture area. In experiments on spray coating, the difference between the thicknesses of resist films deposited on top and bottom trench surfaces is decreased. On the trench sidewall, resist bump formation, which is frequently observed in spray coating, is suppressed. The profile of the resist film becomes conformal and uniform. Such resist deposition is necessary to realize 3D microdevices. In microfluidic devices using dielectrophoresis, aside from the top and bottom trench surfaces, the trench sidewall can be used for preparing device structures such as electrode. Electric interaction is enhanced for controlling the transport of micro-/nano-scale objects in micro-trench structures.

Biodegradable three-dimension micro-device delivering 5-fluorouracil in tumor bearing mice

A novel three-dimension micro-device was formulated to control delivery of 5-fluorouracil (5-FU) for the treatment of solid tumors. The poly-(lactic-co-glycolic) acid (PLGA), which is both biocompatible and biodegradable, was used as carrier material. The characteristics of drug release in vitro and in vivo and the performance of the micro-device after implantation in tumor bearing mice were evaluated. A constant release profile from in vitro test was obtained for a period of 7 days, and it correlated well with the in vivo release profile. In the distribution experiment of 5-FU micro-device, it was demonstrated that 5-FU remained in the tumor tissues for more than 7 days after implantation. Likewise, we found that the 5-FU concentration in tumor correlated well with the in vivo release. Tumors treated with 5-FU loaded micro-device of three different dosages showed significant tumor reduction (P < 0.05) compared with empty control micro-device 7 days after administration. Moreover, the implantation treatment showed enhanced efficacy compared with the intraperitoneal administration with the same dosage. These results suggested that the three-dimensional micro-device may provide a promising local and controlled release drug delivery system, which may enable delivery of multiple drugs for post-surgical chemotherapy against solid tumor.

F221005 マイクロ・ナノ光造形・鋳型技術の開発とその応用

Microstereolithography has been widely applied for a lot of applications such as photonics, MEMS and lab-on-a-chip. The remaining issues of microstereolithography are improvement of both throughput and material limitation. To overcome these issues, we have developed soft and hard molding processes based on one- and two-photon microstereolithography. By using the soft molding process with silicone mold, movable micromachines can be replicated. In addition, the hard molding using a polymeric mold can produce ceramic three-dimensional microdevices such as microchannels, scaffolds, and piezoelectric energy harvesters. These molding processes based on microstereolithography will be useful for mass production of practical devices using various kinds of ceramic materials.

Parallel microassembly with a robotic manipulation system

This paper proposes a methodology to assemble multiple micro-components simultaneously with a robotic manipulator using a parallel assembly method. Through manipulating and assembling the micro-components, intricate, out-of-plane, three-dimensional micro-devices can now be fabricated. Use of a parallel microassembly process rather that a serial approach can significantly increase the productivity and reduce the cost of assembling micro-devices. The parallel microassembly operation proposed in this work was developed and implemented on a 6-DOF robot manipulator to attain considerable manufacturing flexibility. In this study, three passive microgrippers were bonded in parallel to the end-effector of the manipulator. Three microparts were then grasped by the grippers from the worktable of the manipulator, rotated 90°, and assembled onto the base substrate simultaneously. During the parallel microassembly operation, the visual image may not be able to monitor all three gripper-part pairs simultaneously due to the limited field of view of the microscope. Through the use of an alignment-calibration algorithm with only one gripper-part set, the remaining two sets were successfully manipulated and inserted onto the desired assembly location.

Jet molding system for realization of three-dimensional micro-structures

We have developed a fabrication technology for realization of three-dimensional microstmctures composed of different materials using excimer laser ablation and ultrafine particle (UFP) jet molding. We have named this technology the jet molding system (JMS). This method enables the production of three-dimensional microdevices composed of actuator, sensor materials (PZT), and electrodes (metal). Insertmolding and mask-deposition methods were applied to obtain these structures. SEM observation as well as density and electrical property measurements showed good pattern transfer fidelity with sufficient deposited layer quality (density of better than 85%, dielectric constant of deposited PZT layer of 760). The deposition rate of PZT was much faster than that obtained using any other deposition technique, and a PZT layer up to 40 μm of thick was formed with the desired metal electrode structure.

Manufacture of three-dimensional microdevices using synchrotron radiation (invited)

Future innovative microdevices and microsystems require manufacturing processes which allow a high degree of freedom in the geometrical design of the microstructure, a broad spectrum of materials, and a favorable potential for mass production at low costs. These requirements are met by the LIGA process, which uses synchrotron radiation lithography to produce extremely precise masters of three-dimensional microstructures and subsequent electroforming and moulding processes to produce microdevices from metals, polymers, and ceramics. In this article, the basic process principles, its physical and technological limits, and some specific applications such as sensors for automotive purposes, infrared optical components, optical demultiplexers, and fiber-chip coupling elements for optical communication systems, micronozzles and valves, electrical microconnectors, or moving microdevices are discussed.