While over half a century has passed since the introduction of enzyme glucose biosensors by Clark and Lyons, this important field has continued to be the focus of immense research activity. Extensive efforts during the past decade have led to major scientific and technological innovations towards tight monitoring of diabetes. Such continued progress toward advanced continuous glucose monitoring platforms, either minimal- or non-invasive, holds considerable promise for addressing the limitations of finger-prick blood testing toward tracking glucose trends over time, optimal therapeutic interventions, and improving the life of diabetes patients. However, despite these major developments, the field of glucose biosensors is still facing major challenges. The scope of this review is to present the key scientific and technological advances in electrochemical glucose biosensing over the past decade (2010-present), along with current obstacles and prospects towards the ultimate goal of highly stable and reliable real-time minimally-invasive or non-invasive glucose monitoring. After an introduction to electrochemical glucose biosensors, we highlight recent progress based on using advanced nanomaterials at the electrode-enzyme interface of three generations of glucose sensors. Subsequently, we cover recent activity and challenges towards next-generation wearable non-invasive glucose monitoring devices based on innovative sensing principles, alternative body fluids, advanced flexible materials, and novel platforms. This is followed by highlighting the latest progress in the field of minimally-invasive continuous glucose monitoring (CGM) which offers real-time information about interstitial glucose levels, by focusing on the challenges toward developing biocompatible membrane coatings to protect electrochemical glucose sensors against surface biofouling. Subsequent sections cover new analytical concepts of self-powered glucose sensors, paper-based glucose sensing and multiplexed detection of diabetes-related biomarkers. Finally, we will cover the latest advances in commercially available devices along with the upcoming future technologies.

Electrochemical glucose sensors in diabetes management: an updated review (2010-2020).

The ever-increasing demands for clean and sustainable energy sources combined with rapid advances in biointegrated portable or implantable electronic devices have stimulated intensive research activities in enzymatic (bio)fuel cells (EFCs). The use of renewable biocatalysts, the utilization of abundant green, safe, and high energy density fuels, together with the capability of working at modest and biocompatible conditions make EFCs promising as next generation alternative power sources. However, the main challenges (low energy density, relatively low power density, poor operational stability, and limited voltage output) hinder future applications of EFCs. This review aims at exploring the underlying mechanism of EFCs and providing possible practical strategies, methodologies and insights to tackle these issues. First, this review summarizes approaches in achieving high energy densities in EFCs, particularly, employing enzyme cascades for the deep/complete oxidation of fuels. Second, strategies for increasing power densities in EFCs, including increasing enzyme activities, facilitating electron transfers, employing nanomaterials, and designing more efficient enzyme-electrode interfaces, are described. The potential of EFCs/(super)capacitor combination is discussed. Third, the review evaluates a range of strategies for improving the stability of EFCs, including the use of different enzyme immobilization approaches, tuning enzyme properties, designing protective matrixes, and using microbial surface displaying enzymes. Fourthly, approaches for the improvement of the cell voltage of EFCs are highlighted. Finally, future developments and a prospective on EFCs are envisioned.

https://hal-amu.archives-ouvertes.fr/hal-02167914/document

Tackling the Challenges of Enzymatic (Bio)Fuel Cells

In the past few years, 3D printing technology has witnessed an explosive growth, penetrating various aspects of our lives. Current best-in-class 3D printers can fabricate micrometer scale objects, which has made fabrication of microfluidic devices possible. The highest achievable resolution is already at nanometer scale, which is continuing to drop. Since geometric complexity is not a concern for 3D printing, novel 3D microfluidics and lab-on-a-chip systems that are otherwise impossible to produce with traditional 2D microfabrication technology have started to emerge in recent years. In this review, we first introduce the basics of 3D printing technology for the microfluidic community and then summarize its emerging applications in creating novel microfluidic devices. We foresee widespread utilization of 3D printing for future developments in microfluidic engineering and lab-on-a-chip technology.

3D printing: an emerging tool for novel microfluidics and lab-on-a-chip applications

Lubricating oil conditioning sensors for online machine health monitoring – A review

In the prosthetics field, one of the most important bottlenecks is still the human-machine interface, namely the socket. Indeed, a large number of amputees still rejects prostheses or points out a low satisfaction level, due to a sub-optimal interaction between the socket and the residual limb tissues. The aim of this paper is to describe the main parameters (displacements, stress, volume fluctuations and temperature) affecting the stump-socket interface and reducing the comfort/stability of limb prostheses. In this review, a classification of the different socket types proposed in the literature is reported, together with an analysis of advantages and disadvantages of the different solutions, from multiple viewpoints. The paper then describes the technological solutions available to face an altered distribution of stresses on the residual limb tissues, volume fluctuations affecting the stump overtime and temperature variations affecting the residual tissues within the socket. The open challenges in this research field are highlighted and the possible future routes are discussed, towards the ambitious objective of achieving an advanced socket able to self-adapt in real-time to the complex interplay of factors affecting the stump, during both static and dynamic tasks.

/pdf/sockets-for-limb-prostheses-a-review-of-existing-rl8nuxc0cu.pdf

Sockets for Limb Prostheses: A Review of Existing Technologies and Open Challenges

Detection of small metallic wear debris is critical to identify abnormal wear conditions for prognosis of pending machinery failure. In this paper we applied an inductance–capacitance (LC) resonance method to an inductive pulse debris sensor to increase the sensitivity. By adding an external capacitor to the sensing coil of the sensor, a parallel LC resonance circuit is formed that has a unique resonant frequency. At an excitation frequency close to the resonant frequency, impedance change (and thus change in voltage output) of the LC circuit caused by the passage of a debris particle is amplified due to sharp change in impedance at the resonant peak; thus signal-to-noise ratio and sensitivity are significantly improved. Using an optimized measurement circuit, iron particles ranging from 32 to 96 µm and copper particles ranging from 75 to 172 µm were tested. Results showed that the parallel LC resonance method is capable of detecting a 20 µm iron particle and a 55 µm copper particle while detection limits for the non-resonance method are 45 and 125 µm, respectively. In contrast to the non-resonant method, the sensitivity of the resonance method has been significantly improved.

https://iopscience.iop.org/article/10.1088/0957-0233/24/7/075106/pdf

Improving Sensitivity of an Inductive Pulse Sensor for Detection of Metallic Wear Debris in Lubricants Using Parallel LC Resonance Method

We report here a novel two-stage i-DLD sorter through coupling inertial microfluidics with deterministic lateral displacement (DLD), allowing for precise, continuous, and size-based cell separation. The first stage spiral inertial microfluidic sorter is responsible for removing the overwhelming majority of background blood cells at a high-throughput manner. The precise and flow-rate insensitive DLD sorter with triangular posts serves as the second stage sorter which further removes the residual blood cells for obtaining high-purity tumor cells. After demonstrating the conceptual design, we characterize the performances of our two-stage i-DLD sorter for the separation of differently sized particles and cells. The characterization results show that a 100% complete separation of 15 and 7 μm particles was achieved, whereas a separation efficiency of over 99.9% and a target sample purity of 93.59% was realized for the separation of differently sized cells. Finally, we successfully apply our sorter for the separation of rare tumor cells from the diluted whole blood or WBCs at good performances. Our two-stage i-DLD sorter offers numerous advantages of label- and external field-free operation, high-efficiency and high-reliability separation, and high-throughput processing without clogging, and is promising as a potential tool for precise cell separation in low-resource settings.

Precise Size-Based Cell Separation via the Coupling of Inertial Microfluidics and Deterministic Lateral Displacement

Visual detection of mixed organophosphorous pesticide using QD-AChE aerogel based microfluidic arrays sensor

With a long time goal of detecting signs of potential machine failure, we demonstrate a proof-of-principle multiplexed, multichannel, inductive pulse sensor based on resonant frequency division multiplexing for high throughput detection of micro-scale metallic debris in lubricants. In the four-channel sensor, each sensing coil is connected to a specific external capacitance to form a parallel LC circuit that has a unique resonant frequency. Only one combined sinusoidal excitation signal consisting of four frequencies components that are close to the 4 sensing channels’ resonant frequencies was applied to the sensor, and only one combined voltage response was measured. Because each sensing channel exhibited a peak amplitude at its resonant frequency, the signals for each individual channel were recovered from the combined response by taking the spectrum components at each resonant frequency with an improved signal-to-noise ratio. Inductance change for each channel was then calculated from signals of individual channels. Testing results show that the use of resonant frequency division multiplexing allows simultaneous detection of debris in lubricants using only one set of detection electronics; for the four-channel sensor, there is a 300 % increase in throughput. The resonant frequency division multiplexing concept can be potentially applied to a multichannel oil debris sensor with a large number of sensing channels to achieve a very high throughput, which is necessary for online health monitoring of rotating and reciprocal mechanical components.

High Throughput Wear Debris Detection in Lubricants Using a Resonance Frequency Division Multiplexed Sensor

A zwitterionic poly(sulfobetaine-3,4-ethylenedioxythiophene) (PSBEDOT)-based glucose biosensor was fabricated via encapsulating glucose oxidase (GOx) in a one-step electropolymerization method. Integrating conductivity and hydrophilic properties, PSBEDOT provides a great framework for GOx immobilization and stabilization. The anti-fouling, high-sensitivity, and long-term stability properties of PSBEDOT–GOx make it a promising platform for long-term and continuous glucose monitoring.

/pdf/highly-sensitive-and-stable-zwitterionic-poly-sulfobetaine-3-37eh1kjb35.pdf

Yu Han

Papers

Improving Sensitivity of an Inductive Pulse Sensor for Detection of Metallic Wear Debris in Lubricants Using Parallel LC Resonance Method

Precise Size-Based Cell Separation via the Coupling of Inertial Microfluidics and Deterministic Lateral Displacement

Visual detection of mixed organophosphorous pesticide using QD-AChE aerogel based microfluidic arrays sensor

High Throughput Wear Debris Detection in Lubricants Using a Resonance Frequency Division Multiplexed Sensor

Highly sensitive and stable zwitterionic poly(sulfobetaine-3,4-ethylenedioxythiophene) (PSBEDOT) glucose biosensor.