On-chip Isolation Research Articles

A Method for Improving Reflection Tolerance of Laser Source in Hybrid Photonic Packaged Micro-System

In multi-chip integrated photonic micro-systems, it is important to protect the laser source from reflection because the semiconductor laser is sensitive to the back reflection induced by the roughness of the waveguide sidewall or other on-chip optical structures. In order to maintain the stable operation of the light source, an additional micro-ring resonator coupled with the laser source is design before the optical circuit which enables the laser diode to enter a self-injection locking state and improves the reflection tolerance. It is experimentally demonstrated in the hybrid system that by tuning the phase shifter and the micro-ring resonate wavelength, the distributed feedback (DFB) laser enters a self-injection locking state, resulting significant improvement of the critical reflection ratio from −18.69 dB to −4.31 dB. The method can isolate the external reflection of laser diode without using heterogeneous integration, which provides a new idea for on-chip source isolation. The parameters design of the micro-ring and the coupling method with the laser are also introduced in the letter.

Isolation of primary brain endothelial cells, pericytes and astrocytes on a microfluidic immunopanning chip (MIC)

Brain microvascular cells such as brain microvascular endothelial cells (BMEC), pericytes, and astrocytes are major components of the blood–brain barrier (BBB). The BBB regulates substance transport from the blood into the brain and is involved in the progression of many neurological diseases. This has led to significant interest in developing in vitro models to study the characteristics of brain primary microvascular cells and the BBB. However, BMECs only account for 1–2% of the total cell population in the brain and are extremely difficult to obtain. We report a microfluidic immunopanning chip (MIC) for the on-chip isolation and purification of multiple types of primary brain microvascular cells simultaneously. The cell isolation efficiency and purity achieved with the MIC are higher compared with conventional bench-top immunopanning method. We incorporated microcarriers in the MIC as a means to increase cell capturing efficiency and a substrate for subsequent cell culture. With low reagents consumption, multiplexing capabilities, and high isolation efficiency, the MIC shows great potential as a tool for rare cell isolation and have potential broader applications in cell therapy.

An automated centrifugal microfluidic assay for whole blood fractionation and isolation of multiple cell populations using an aqueous two-phase system.

Fractionating whole blood and separating its constituent components one from another is an essential step in many clinical applications. Currently blood sample handling and fractionation processes remain a predominantly manual task that require well-trained operators to produce reliable and reproducible results. Herein, we demonstrate an advanced on-chip whole human blood fractionation and cell isolation process combining (i) an aqueous two-phase system (ATPS) to create complex separation layers with (ii) a centrifugal microfluidic platform (PowerBlade) with active pneumatic pumping to control and automate the assay. We use a polyethylene glycol (PEG) and dextran (DEX) mixture as the two-phase density gradient media and our automated centrifugal microfluidic platform to fractionate blood samples. Different densities of precisely tuned PEG-DEX solutions were tested to match each of the cell types typically targeted during blood fractionation applications. By employing specially designed microfluidic devices, we demonstrate the automation of the following steps: loading of a whole blood sample on-chip, layering of the blood on the ATPS solution, blood fractionation, precise radial repositioning of the fractionated layers, and finally extraction of multiple, selected fractionated components. Fractionation of up to six distinct layers is shown: platelet-rich plasma, buffy coat, PEG, DEX with neutrophils, red blood cells (RBCs) and high density gradient media (HDGM). Furthermore, through controlled dispensing of HDGM to the fractionation chamber, we show that each of the fractionated layers can be repositioned radially, on-the-fly, without disturbing the interfaces, allowing precise transfer of target fractions and cell types into external vials via a chip-to-world interface. Cell counting analysis and cell viability studies showed equivalence to traditional, manual methods. An overall cell viability greater than 90% of extracted cells demonstrates that the proposed approach is suitable for cell isolation applications. This proof-of-principle demonstration highlights the utility of the proposed system for automated whole blood fractionation and isolation for blood cell applications. We anticipate that the proposed approach will be a useful tool for many clinical applications such as standard cell isolation procedures and other bioanalytical assays (e.g., circulating tumor cells, and cell and gene therapy).

Simultaneous on-chip isolation and characterization of circulating tumor cell sub-populations

The diagnosis of tumor metastasis using circulating tumor cells (CTCs) has been considered an important developmental target for several decades but remains a formidable challenge because of the rarity and heterogeneity of CTCs. Additional downstream analysis is required after isolating CTCs on-chip for subtype verification. To solve those problems, we have developed microfluidic based integrated system which uses magnetic field gradient and immune-fluorescence differences to on-chip isolation and discrimination of CTCs simultaneously. The system presented in the present study can isolate CTCs with an efficiency of >99% by utilizing magnetic nanoparticles conjugated to CTC membranes. Furthermore, the statuses of three biomarkers can be determined on-chip simultaneously. The devised microfluidic system can differentiate eight different subtypes of heterogenic CTCs by on-chip isolation and based on the statuses of three biomarkers (HER2, ER, and PR) which are critical variables to five-year overall survivals for breast cancer patients.

Integrated microwave acousto-optic frequency shifter on thin-film lithium niobate

Electrically driven acousto-optic devices that provide beam deflection and optical frequency shifting have broad applications from pulse synthesis to heterodyne detection. Commercially available acousto-optic modulators are based on bulk materials and consume Watts of radio frequency power. Here, we demonstrate an integrated 3-GHz acousto-optic frequency shifter on thin-film lithium niobate, featuring a carrier suppression over 30 dB. Further, we demonstrate a gigahertz-spaced optical frequency comb featuring more than 200 lines over a 0.6-THz optical bandwidth by recirculating the light in an active frequency shifting loop. Our integrated acousto-optic platform leads to the development of on-chip optical routing, isolation, and microwave signal processing.

Parametric study on the geometrical parameters of a lab-on-a-chip platform with tilted planar electrodes for continuous dielectrophoretic manipulation of microparticles

Advances in lab-on-a-chip (LOC) devices have led to significant improvements in the on-chip manipulation, separation, sorting, and isolation of particles and cells. Among various LOC-based approaches such as inertia-based methods, acoustophoresis, and magnetophoresis, the planar-slanted-electrode dielectrophoresis (DEP) method has demonstrated great potential as a label-free, cost-effective, and user-friendly approach. However, the devices built based on this method suffer from low flow throughput compared to devices functioning based on other LOC-based manipulation approaches. In order to overcome this obstacle, the geometrical parameters of these types of DEP-based devices must be studied to increase the effectiveness of DEP manipulation. With the consideration of both numerical and experimental studies, this paper studies the geometrical factors of a LOC platform consisting of tilted planar electrodes with the goal of achieving higher throughput in continuous manipulation of polystyrene particles. COMSOL Multiphysics software was used to study the effect of the electrodes geometry on the induced electric field. The simulation results show that by increasing the electrode’s width and decreasing the electrode’s spacing, higher DEP force is generated. Furthermore, the experimental outcomes indicated that lower channel height, higher voltage, and larger particle size resulted in the most improvement to DEP manipulation. Additionally, the experimental results demonstrated that slanted electrodes with an angle of 8° with respect to the direction of flow provide a more effective configuration.

Integrated Microfluidic Device for Accurate Extracellular Vesicle Quantification and Protein Markers Analysis Directly from Human Whole Blood.

Extracellular vesicles (EVs) have the potential to be utilized as disease-specific biomarkers. Although strategies for on-chip isolation and detection of EVs have recently been developed, they need preprocessing of clinical samples and are not accurate enough for disease diagnosis just judging by EVs concentration. Here, we designed an integrated microfluidic device named a plasma separation and EV detection (PS-ED) chip for plasma separation, quantification, and high-throughput protein analysis of EVs directly from clinical whole blood samples. The device included two modules (PS and ED module): the PS module was a six-loop microchannel for rapid separation of plasma from clinical whole blood samples under inertial force; the amount of EVs in the separated plasma kept the same value as in the initial blood samples. The module reduced the mechanical damage to the blood cells and thus reduced the interference of debris or cellular contents from damaged cells during EVs detection; the ED module contained four S-channels for quantification and high-throughput protein analysis of EVs; a wide detection range from 2.5 × 102 to 2.5 × 108 particles/μL with a detection limit of 95 particles/μL was obtained. Through simultanously monitoring three proteins (CD81, CD24, and EpCAM) of EVs, the cancer type can be accurately confirmed. Furthermore, clinical blood sample analysis verified that the proposed device could be used for accurate diagnosis and therapy monitoring of ovarian cancer.

Isolation and Profiling of Circulating Tumor-Associated Exosomes Using Extracellular Vesicular Lipid-Protein Binding Affinity Based Microfluidic Device.

Extracellular vesicles (EVs) are emerging as a potential diagnostic test for cancer. Owing to the recent advances in microfluidics, on-chip EV isolation is showing promise with respect to improved recovery rates, smaller necessary sample volumes, and shorter processing times than ultracentrifugation. Immunoaffinity-based microfluidic EV isolation using anti-CD63 is widely used; however, anti-CD63 is not specific to cancer-EVs, and some cancers secrete EVs with low expression of CD63. Alternatively, phosphatidylserine (PS), usually expressed in the inner leaflet of the lipid bilayer of the cells, is shown to be expressed on the outer surface of cancer-associated EVs. A new exosome isolation microfluidic device (new ExoChip), conjugated with a PS-specific protein, to isolate cancer-associated exosomes from plasma, is presented. The device achieves 90% capture efficiency for cancer cell exosomes compared to 38% for healthy exosomes and isolates 35% more A549-derived exosomes than an anti-CD63-conjugated device. Immobilized exosomes are then easily released using Ca2+ chelation. The recovered exosomes from clinical samples are characterized by electron microscopy and western-blot analysis, revealing exosomal shapes and exosomal protein expressions. The new ExoChip facilitates the isolation of a specific subset of exosomes, allowing the exploration of the undiscovered roles of exosomes in cancer progression and metastasis.

A Carrier Aggregation Transmitter Front End for 5-GHz WLAN 802.11ax Application in 40-nm CMOS

Carrier aggregation will be a key feature of the emerging 802.11ax system to boost data rate. Voltage-controlled oscillator (VCO) pulling and crosstalk between RF channels are two main problems related to carrier aggregation, which introduce severe impacts on adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM). To address these two problems, high isolation between transmitter channels is required, but may not be realizable in some practical cases due to the constraint of the layout. This article presents a transmitter front end that can support two-carrier aggregation for 802.11ax without high on-chip isolation. The proposed transmitter front end employs a parallel direct conversion and double conversion configuration, and two carriers are combined before the power amplifier (PA). In this way, the intrinsic problems of VCO pulling and crosstalk can be mitigated. The proposed transmitter front end was implemented in a 40-nm CMOS technology. For contiguous intraband carrier aggregation with VHT80, MCS9 signals [80-MHz bandwidth, 256-quadrature amplitude modulation (QAM), and 11.25-dB peak-to-average power ratio (PAPR)], the transmitter front end delivers an average output power of 5.3 + 4.8 dBm for two carriers with an EVM of ≤−32 dB, and the EVM can reach −36.1 dB.

Microfluidic device for on-chip isolation and detection of circulating exosomes in blood of breast cancer patients.

Tumor-derived circulating exosomes have been recognized as a promising biomarker source for cancer diagnosis via a less invasive procedure. The integration of isolation and detection of exosomes in routine clinical settings is still challenging. In this study, we developed a new microfluidic device for immunomagnetic separation and detection of blood exosomes in situ. The microfluidic device may empower the integration of target exosome analysis via high surface to volume ratios of immunomagnetic beads and highly precise fluid control with the aid of microvalves. The obtained microfluidic device was capable of on-chip isolation and detection of circulating exosomes within 1.5 h. The captured exosomes could be directly visualized with an inverted fluorescence microscope in situ by tetramethylbenzidine-based colorimetric sensing. It was revealed that a statistically significant increase (p < 0.01) in EpCAM-positive exosomes was captured for cancer patients (n = 10) on the device when compared to healthy individuals (n = 10). The device also demonstrated high predicting accuracy for tumor exosomal markers with a sensitivity of 90% and a specificity of >95% using receiver operating characteristic curves. The microfluidic device might provide a new platform to assist cancer diagnosis and molecular classification in an automated and simple fashion.

Abstract 2437: Microfluidic device integrated with lipid nanoprobe for extracellular vesicle isolation toward non-invasive cancer diagnosis

Abstract Extracellular vesicles (EVs) can mediate intercellular communication by transferring cargo proteins and nucleic acids between cells. Recently, they have been demonstrated for potential value in cancer diagnostics and treatment monitoring. However, relevant clinical translation is mainly limited by technical challenges in EV isolation. We previously reported lipid nanoprobes, which is a nanomaterial system of labeling probe and capture probe. The labeling probe is constructed with a lipid molecule as the active component to label EVs rapidly and spontaneously with high efficiency, while the capture probe can isolate labeled EVs magnetically. Herein, we report on the development of a microfluidic device with integrated lipid nanoprobe for on-chip EV isolation towards instrument development for clinical translation. The nanostructured substrate of the device is integrated with a micromixer for one-step isolation of EVs from 1-ml plasma. We validated the device with plasma collected from pancreatic cancer patients, followed by DNA mutation detection of EV cargo. Size-tunable nanostructures are fabricated by patterning high-resolution iron thin films on fused silica substrates. By judicious thermal annealing, homogeneously dispersed iron nanoparticles are formed by fission and fusion on the substrate, which are served as a mask for silica dry-etching. Subsequently, selected lipid nanoprobes, which can instantaneously insert into lipid bilayers of EVs, are grafted onto the nanostructured substrate in a micromixer. This platform is verified first to isolate cultured cancer cell-derived EVs spiked-in plasma samples that emulated clinical samples. This platform is further applied to isolate EVs from pancreatic cancer patients’ plasma and identified KRASmutations in EV DNA with highly sensitive droplet digital PCR. Together, this platform enables rapid and efficient isolation of EVs from plasma specimens, and thus, holds great potential in clinical translation. Citation Format: Siyang Zheng, Yuan Wan, Mackenzie Maurer, Yi-Qiu Xia, Si-Jie Hao, Wen-Long Zhang, Nelson S. Yee. Microfluidic device integrated with lipid nanoprobe for extracellular vesicle isolation toward non-invasive cancer diagnosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2437.

A 50-V Isolation, 100-MHz, 50-mW Single-Chip Junction Isolated DC-DC Converter With Self-Tuned Maximum Power Transfer Frequency

A fully integrated, point-of-load, low-noise, isolated dc–dc converter for supply regulation of high dynamic range analog and mixed-signal isolated sensor signal-chains is presented. The isolated dc–dc converter utilizes an integrated planar air-core micro-transformer as a coupled-resonator and an isolation barrier, and enables direct connection of low-voltage mixed-signal circuits to higher supply rails for current and voltage sensing. The transformer is driven at its resonant frequency of 100 MHz to achieve maximum power transfer. A mixed-signal perturb-and-observe-based frequency search algorithm is developed to improve maximum power transfer efficiency by 60% across the isolation barrier compared to fixed driving frequency method. The switching ripple at output is reduced by 11 dB utilizing spread spectrum clocking in the driver, and 21 dB using a low-dropout regulator. Conducted and radiated EMI distribution on the IC is measured by a set of proposed ring oscillator-based noise sensors with −68-dBm noise sensitivity. The proposed isolated converter achieves the highest level of integration compared to state-of-the-art integrated isolated converters, and provides 50-V on-chip junction isolation using standard CMOS technology.

On-chip isolation and enrichment of circulating cell-free DNA using microfluidic device.

Circulating cell-free DNA (cfDNA), containing cancer-specific DNAs derived from tumor cells, plays an important role in real-time monitoring of disease progression. Due to the abnormal growth of cancer and the promotion of cancer cell apoptosis by chemotherapy, the higher cfDNA concentration than healthy individuals is closely correlated with the diagnosis and treatment of cancer. Also, the mutation detection in tumor cell-derived cfDNA can be used to predict tumor progression. Human blood contains many blood cells (red blood cells, white blood cells, and platelets), proteins, extracellular vesicles, and so on. These blood components act as the inhibitors when the cfDNA is analyzed using polymerase chain reaction. So, analysis of cfDNA using whole blood directly may affect the sensitivity of the analysis or result in false-negative. The conventional methods of cfDNA isolation, such as silica absorption and polymer-mediated enrichment, are labor-intensive and time-consuming processes that can also lead to the loss of cfDNA in cumbersome procedures. Here, we designed an integrated microfluidic chip capable of on-chip cfDNA extracting to reduce sample loss and processing time. Our proposed device minimizes the number of experimental steps from 5 to 1, the total processing time from 42 to 19 min, and the required volume of washing reagents from 2 to 0.4 ml for cfDNA enrichment compared to the conventional method.

Emerging Nanotechnologies for Liquid Biopsy: The Detection of Circulating Tumor Cells and Extracellular Vesicles.

Liquid biopsy enables noninvasive and dynamic analysis of molecular or cellular biomarkers, and therefore holds great potential for the diagnosis, prognosis, monitoring of disease progress and treatment efficacy, understanding of disease mechanisms, and identification of therapeutic targets for drug development. In this review, the recent progress in nanomaterials, nanostructures, nanodevices, and nanosensors for liquid biopsy is summarized, with a focus on the detection and molecular characterization of circulating tumor cells (CTCs) and extracellular vesicles (EVs). The developments and advances of nanomaterials and nanostructures in enhancing the sensitivity, specificity, and purity for the detection of CTCs and EVs are discussed. Sensing techniques for signal transduction and amplification as well as visualization strategies are also discussed. New technologies for the reversible release of the isolated CTCs and EVs and for single-CTC/EV analysis are summarized. Emerging microfluidic platforms for the integral on-chip isolation, detection, and molecular analysis are also included. The opportunities, challenges, and prospects of these innovative materials and technologies, especially with regard to their feasibility in clinical applications, are discussed. The applications of nanotechnology-based liquid biopsy will bring new insight into the clinical practice in monitoring and treatment of tumor and other significant diseases.

Photonic Integrated Circuits Using Heterogeneous Integration on Silicon

Heterogeneous silicon photonics using wafer bonding is reaching maturity with commercial products for the data center market being shipped in volume. Here we give an overview of recent research in the area showing record device performance by using the best of both worlds: III–V for light generation and Si for guiding the light. Utilizing the flexibility of the heterogeneous silicon platform, narrow-linewidth widely tunable lasers as well as fully integrated mode locked lasers with record pulse powers and pulse duration were demonstrated. The ability to perform multiple die bonding with optimized epitaxially grown layer stacks was used to realize high-performance photonic integrated circuits both for communications and sensing. In addition to III–V materials, nonreciprocal materials such as, for example, Ce:YIG can be bonded, providing additional functionality such as on-chip isolators and reconfigurable on-chip circulators. On-chip isolation will become necessary with the increase in complexity of photonic integrated chips as photonic components such as lasers are sensitive to feedback effects.

On-Chip Interference Generation Mechanisms From an Electromagnetic Perspective

The electromagnetic characterization of on-chip interference generation mechanisms provides new and valuable insights to deal with substrate coupling. In this paper, we describe interference generation from a new perspective that allows us to determine which are the dominant contributions to substrate coupling as a function of the substrate technology option, the device architecture, and the specific operational configuration. This approach is also used to assess the effectiveness of on-chip isolation structures as a function of the aggressor and different grounding strategies. From this analysis, design recommendations are derived to minimize substrate-induced interference.

ScFTD-seq: freeze-thaw lysis based, portable approach toward highly distributed single-cell 3' mRNA profiling.

Cellular barcoding of 3′ mRNAs enabled massively parallel profiling of single-cell gene expression and has been implemented in droplet and microwell based platforms. The latter further adds the value for compatibility with low input samples, optical imaging, scalability, and portability. However, cell lysis in microwells remains challenging despite the recently developed sophisticated solutions. Here, we present scFTD-seq, a microchip platform for performing single-cell freeze-thaw lysis directly toward 3′ mRNA sequencing. It offers format flexibility with a simplified, widely adoptable workflow that reduces the number of preparation steps and hands-on time, with the quality of data and cost per sample matching that of the state-of-the-art scRNA-seq platforms. Freeze-thaw, known as an unfavorable lysis method resulting in possible RNA fragmentation, turns out to be fully compatible with 3′ scRNA-seq. We applied it to the profiling of circulating follicular helper T cells implicated in systemic lupus erythematosus pathogenesis. Our results delineate the heterogeneity in the transcriptional programs and effector functions of these rare pathogenic T cells. As scFTD-seq decouples on-chip cell isolation and library preparation, we envision it to allow sampling at the distributed sites including point-of-care settings and downstream processing at centralized facilities, which should enable wide-spread adoption beyond academic laboratories.

Magnetic-Based Microfluidic Device for On-Chip Isolation and Detection of Tumor-Derived Exosomes.

Exosomes are membrane-enclosed phospholipid extracellular vesicles, which can act as mediators of intercellular communication. Although the original features endow tumor-derived exosomes great potential as biomarkers, efficient isolation and detection methods remain challenging. Here, we presented a two-stage microfluidic platform (ExoPCD-chip), which integrates on-chip isolation and in situ electrochemical analysis of exosomes from serum. To promote exosomes capture efficiency, an improved staggered Y-shaped micropillars mixing pattern was designed to create anisotropic flow without any surface modification. By combining magnetic enrichment based on specific phosphatidylserine-Tim4 protein recognition with a new signal transduction strategy in a chip for the first time, the proposedplatform enables highly sensitive detection for CD63 positive exosomes as low as 4.39 × 103 particles/mL with a linear range spanning 5 orders of magnitude, which is substantially better than the existing methods. The reduced volume of sample (30 μL) and simple affinity method also make it ideal for rapid downstream analysis of complex biofluids within 3.5 h. As a proof-of-concept, we performed exosomes analysis in human serum and liver cancer patients can be well discriminated from the healthy controls by the ExoPCD-chip. These results demonstrate that this proposed ExoPCD-chip may serve as a comprehensive exosome analysis tool and potential noninvasive diagnostic platform.

Hardware-Assisted Security in Electronic Control Units: Secure Automotive Communications by Utilizing One-Time-Programmable Network on Chip and Firewalls

With emerging smart automotive technologies, vehicle-to-vehicle communications, and software-dominated enhancements for enjoyable driving and advanced driver assistance systems, the complexity of providing guarantees in terms of security, trust, and privacy in a modern cyber-enabled automotive system is significantly elevated. New threat models emerge that require efficient system-level countermeasures. This article introduces synergies between on- and off-chip networking techniques to ensure secure execution environments for electronic control units. The proposed mechanisms consist of hardware firewalling and on-chip network physical isolation, whose mechanisms are combined with system-wide cryptographic techniques in automotive controller area network (CAN)-bus communications to provide authentication and confidentiality.

On-chip optical isolator based on unidirectional wavelength-mode conversion waveguide

Breaking Lorentz reciprocity is one necessary condition of optical isolator design. Unidirectional wavelength-mode conversion will be realized in a time-dependent system through a short operating range. Based on plasma dispersion effect, generate space-asymmetric periodical time-space modulation on silicon waveguide, and non-reciprocal propagation is realized in the waveguide. The designed unidirectional wavelength-mode conversion waveguide demonstrated that in the forward direction, input 1.55 [Formula: see text]m fundamental mode light signal and then output 1.5492 [Formula: see text]m is of 1st-order mode, while in the backward direction, input 1.5492 [Formula: see text]m is of 1st-order mode light signal and then output 1.5484 [Formula: see text]m is of fundamental mode. Based on this non-reciprocal structure, mode conversion waveguide and two-ring resonance filters were designed then, to accomplish on-chip optical isolation. The scale of the designed isolator is 160 [Formula: see text]m × 60 [Formula: see text]m, and the isolation is 21 dB, revealing perfect application potential.