On-chip mobile microrobotic transducer for high-temporal resolution sensing using dynamics analysis

International audienceUntethered mobile magnetic microrobots in liquids are under increased investigation with the intended goal to obtain in vivo transducing applications, mostly for micromanipulation or cargo transport. Using them as wireless sensors is less common though it offers a highly controllable and mobile sensing capability at micrometric scale with the capability to provide information about their dynamics and interaction with their environment. Here a system is proposed which is fully controllable by calibrated external magnetic fields and high temporal resolution (>5000FPS) visual feedback. With the targeted applications being in microscale fluids, a mobile magnetic microrobot is integrated into an optically transparent microfluidic chip which demonstrates sensing capabilities. In these experiments, physical sensing is quantified through microrobot dynamics analysis of its elementary planar motions (rotary and translational) and these results are related to local viscosity of fluid and friction from the interfaces. These results also allow for the characterization of swimming performances, magnetization and thus help to improve the design of the microrobotic system. An analysis of transition dynamics also provides complementary measurement on the microrobot hydrodynamics and the interaction with its substrate. The proposed on-chip mobile microrobotic system provides an advantageous testing platform to further investigate the visual servo automation control towards their in-vitro or in-vivo applications

Swimming property characterizations of Magnetic Polarizable microrobots

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Using breakdown phenomenon as mobile magnetic field sensor in microfluidics

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Microrobot-in-glass for dynamic motion analysis and wider in vitro applications

International audienceMicrorobots could become a key enabler in life science and medicine research as well as industrial applications. Although they provide high performance tools for a wide range of applications, their environment and particularly surface forces induce significant challenge for their control. We introduce an original integrated microrobot in a permanently sealed glass microfluidic chip. Compared to conventional polymer chips, the glass substrate offers a smooth, stable, and inert surface. It also avoids the typical contamination and fast degradation of organosilicon polymers. In this environment, we demonstrate high frequency hydrodynamics analysis and control. This strategy offers a high precision platform to study microrobot design and hydrodynamics as well as a transducer module for mapping surfaces and sensing interaction with physical environments

Cardiac glycosides use and the risk of lung cancer: a nested case–control study

Background: Two studies have reported statistically significant associations between the use of cardiac glycosides (CGs) and an increased risk of lung cancer. However, these studies had a number of methodological limitations. Thus, the objective of this study was to assess this association in a large population-based cohort of patients. Methods: We used the United Kingdom Clinical Practice Research Datalink (CPRD) to identify a cohort of patients, at least 40 years of age, newly-diagnosed with heart failure, or supra-ventricular arrhythmia. A nested case–control analysis was conducted where each incident case of lung cancer identified during follow-up was randomly matched with up to 10 controls. Exposure to CGs was assessed in terms of ever use, cumulative duration of use and cumulative dose. Rate ratios (RRs) with 95% confidence intervals (CIs) were estimated using conditional logistic regression after adjusting for potential confounders. Results: A total of 129,002 patients were included, and followed for a mean (SD) of 4.7 (3.8) years. During follow-up, 1237 patients were newly-diagnosed with lung cancer. Overall, ever use of CGs was not associated with an increased risk of lung cancer when compared to never use (RR = 1.09, 95% CI: 0.94-1.26). In addition, no dose–response relationship was observed in terms of cumulative duration of use and cumulative dose with all RRs around the null value across quartile categories. Conclusion: The results of this large population-based study indicate that the use of CGs is not associated with an increased risk of lung cance

Multiflagella artificial bacteria for robust microfluidic propulsion and multimodal micromanipulation

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Microcalorimeter fabrication and new measurement methodology for thermal sensing in microfluidics

This work describes the integration of a Resistance Thermal Detector (RTD) microcalorimeter integrated into a 324 nL microfluidic channel. The sensor is fabricated in a clean room using photolithography and evaporation techniques, and it has a platinum serpentine with 60 windings. The RTDs undergo testing in the 30 to 45 °C temperature range, exhibiting great linearity and a sensitivity of 8.42 Ω/°C. Additionally, to perform the thermic measurement, we also provide a circuit architecture that ensures stability against external thermal fluctuations and the self-heating Joule effect. We showed that this measurement method allow us to achieve a precision of ±6.7·10−3 °C, compared to ±0.178 °C total fluctuations found by using the traditional 2-wire method

Electromechanical conversion efficiency of GaN NWs: critical influence of the NW stiffness, the Schottky nano-contact and the surface charge effects

International audienceThe piezoelectric nanowires (NWs) are considered as promising nanomaterials to develop high-efficient piezoelectric generators. Establishing the relationship between their characteristics and their piezoelectric conversion properties is now essential to further improve the devices. However, due to their nanoscale dimensions, the NWs are characterized by new properties that are challenging to investigate. Here, we use an advanced nano-characterization tool derived from AFM to quantify the piezo-conversion properties of NWs axially compressed with a well-controlled applied force. This unique technique allows to establish the direct relation between the output signal generation and the NW stiffness and to quantify the electromechanical coupling coefficient of GaN NWs, which can reach up to 43.4%. We highlight that this coefficient is affected by the formation of the Schottky nano-contact harvesting the piezo-generated energy, and is extremely sensitive to the surface charge effects, strongly pronounced in sub-100 nm wide GaN NWs. These results constitute a new building block in the improvement of NW-based nanogenerator devices

Desmoplastic Small Round Cell Tumor: Current Management and Recent Findings

Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive mesenchymal tumor that develops in the abdominal cavity of young men adults. Patients typically present with symptoms of abdominal sarcomatosis. Diagnosis is based on histological analysis of biopsies which typically show small round blue cells in nests separated by an abundant desmoplastic stroma. DSRCT is associated with a unique chromosomal translocation t(11:22) (p 13; q 12) that involves the EWSR1 and WT1 genes. The prognosis is particularly poor; median survival ranges from 17 to 25 months, largely due to the presentation of the majority of patients with metastatic disease. Management of DSRCT remains challenging and current schemes lack a significant cure rate despite the use of aggressive treatments such as polychemotherapy, debulking surgery and whole abdominal radiation. Several methods are being evaluated to improve survival: addition of chemotherapy and targeted therapies to standard neoadjuvant protocol, completion of surgical resection with HIPEC, postoperative IMRT, treatment of hepatic metastases with [90Y]Yttrium microsphere liver embolization