Dedy H. B. Wicaksono

Cotton fabric-based electrochemical device for lactate measurement in saliva

Lactate measurement is vital in clinical diagnostics especially among trauma and sepsis patients. In recent years, it has been shown that saliva samples are an excellent applicable alternative for non-invasive measurement of lactate. In this study, we describe a method for the determination of lactate concentration in saliva samples by using a simple and low-cost cotton fabric-based electrochemical device (FED). The device was fabricated using template method for patterning the electrodes and wax-patterning technique for creating the sample placement/reaction zone. Lactate oxidase (LOx) enzyme was immobilised at the reaction zone using a simple entrapment method. The LOx enzymatic reaction product, hydrogen peroxide (H2O2) was measured using chronoamperometric measurements at the optimal detection potential (-0.2 V vs. Ag/AgCl), in which the device exhibited a linear working range between 0.1 to 5 mM, sensitivity (slope) of 0.3169 μA mM(-1) and detection limit of 0.3 mM. The low detection limit and wide linear range were suitable to measure salivary lactate (SL) concentration, thus saliva samples obtained under fasting conditions and after meals were evaluated using the FED. The measured SL varied among subjects and increased after meals randomly. The proposed device provides a suitable analytical alternative for rapid and non-invasive determination of lactate in saliva samples. The device can also be adapted to a variety of other assays that requires simplicity, low-cost, portability and flexibility.

Cotton fabric as an immobilization matrix for low-cost and quick colorimetric enzyme-linked immunosorbent assay (ELISA)

Enzyme-linked immunosorbent assay (ELISA) is a reliable quantification assay used in laboratories around the world. The method itself is time consuming and requires a relatively high volume of reagents. In recent years, microfluidics based on paper platforms has been used extensively to develop devices for point of care diagnosis testing. In this work, cloth was used as a superior alternative to paper (stronger, higher controllable rates for fluid mixing and lower environmental impact) to implement ELISA and quantitatively determine human chorionic gonadotropin. The intrinsic properties of cotton fabric allowed the entrapment of the antibody through cloth fibers and showed a superior alternative to common immobilization procedures. The cloth-based ELISA was shown to be feasible to detect human chorionic gonadotropin (0–140 × 10−6 nmol) via image analysis providing a sigmoid fit (R2 = 0.983) of the data and a limit of detection (LOD) of 2.19 ng mL−1. Both the volume of the reagents and the time required for the assay were effectively reduced compared with conventional ELISA. Ultimately, this user-friendly device can potentially be embedded in bandages and gauzes for surgical and clinical settings or in clothing for home care monitoring of elderly and chronic patients.

Biomimetic strain-sensing microstructure for improved strain sensor: fabrication results and optical characterization

This paper describes the fabrication, and early optical characterization results of a new biomimetic strain-sensing microstructure. The microstructures were inspired from the campaniform sensillum, a highly sensitive strain sensor found in the exocuticle layer of insects. We investigate the natural strain-sensor characteristics by mimicking some of its simplest structural features. Blind-hole- and membrane-structural features were combined and fabricated as membrane-in-recess microstructure. To investigate the strain-sensing (or strain-amplifying) property of the microstructure, an optical characterization setup was devised based on the interference pattern formed by reflected laser beams from different surfaces of the microstructures. Preliminary qualitative analysis of the results obtained shows unsimilar intensity level changes as a function of spatial location on the membrane, thus indicated the biomimetic microstructures strain-amplifying property. This property could be utilized for future improvement of currently available planar-based conventional strain sensors.

Proprioceptive Sensing System for Therapy Assessment Using Cotton Fabric-Based Biomedical Microelectromechanical System

Demands for better control of the operating conditions used in human motion tracking and medical applications have led to the need for better means of detecting different types of proprioceptive activity patterns. The purpose of this paper is to propose the development of a proprioceptive sensor for applications in medical system and therapy assessment using cotton fabric-based flexible microelectromechanical systems (MEMS). To demonstrate the application of this sensor, a system has been developed in order to detect different finger flexion movements on a finger joint. The procedure for the development of MEMS proprioceptive sensor fabricated using cotton fabric as the structural material is described. Cotton fabric is chosen as the structural material because it is inexpensive, simple to fabricate, readily available for mass production, lightweight, and conforms to any arbitrary surface. It is also sustainable and environmentally friendly. The fabric is stamped with varied volume of silver nanoparticles (AgNPs) ink to generate different conductive pattern. The working principle of this textile-based sensor is based on piezoresistivity effect generated by the deposited AgNPs on the hierarchical structure of cotton fabric substrate. Based on this fact, this sensor can give sensing information about different finger flexure movements according to the resistance change of the AgNPs. This sensor can be used as a rehabilitation device, e.g., data glove or even a communication device for the disabled to control appliances.

Textile/Al2O3–TiO2 nanocomposite as an antimicrobial and radical scavenger wound dressing

Improving the antimicrobial activity and radical scavenging ability of a textile-based nanocomposite (textile/TiO2, textile/Al2O3/TiO2, textile/Al2O3 and textile/Al2O3–TiO2 bimetal oxide nanocomposite) is the key issue in developing a good and flexible wound dressing. In this work, flexible textile attached with Al2O3–TiO2 nanoparticles was prepared by dipping the textile in a suspension containing Al2O3–TiO2 nanoparticles (150 mmol l−1). The mean radical scavenging ability for textile/TiO2, textile/Al2O3/TiO2, textile/Al2O3 and textile/Al2O3–TiO2 bimetal oxide nanocomposites as measured by liquid ultraviolet visible spectroscopy (UV-Vis) coupled with dependence formula was 0.2%, 35.5%, 35.0% and 38.2%, respectively. Based on the X-ray diffraction (XRD) patterns, the preface reactive oxygen species (ROS) scavenging ability shown by the textile/Al2O3–TiO2 bimetal oxide nanocomposite is most probably caused by the crystal structure concluding in a corundum-like structure, with Al3+ ions filling the octahedral sites in the lattice. Increased antimicrobial activity measured by optical density at 600 nm recorded for textile/Al2O3–TiO2 bimetal oxide nanocomposites showed better interaction between Al2O3 and TiO2 nanoparticles. This good interaction is expected to lead to better antimicrobial and radical scavenging ability as shown by the E. coli and human skin fibroblast (HSF) cytotoxicity tests, respectively.

Fabrication and initial characterisation results of a micromachined biomimetic strain sensor inspired from the Campaniform sensillum of insects

In this report, we present our initial fabrication and characterisation results of a new micromachined biomimetic strain sensor. The new strain sensor is structurally inspired from the natural strain sensor found in insects, commonly called Campaniform sensillum. The high-sensitivity strain sensing capability of Campaniform sensillum is among other things due to its hole-structure, as well as its membrane-in-recess structural features. From previous works in continuum macromechanics, it is widely known that hole-structure amplifies stress and mostly becomes a crack starting point. We fabricated for the first time micromachined Si-based strain-sensing structures inspired from these structural features of Campaniform sensillum. In our initial optical characterisation results of these biomimetic Si-based microstructures, it is confirmed that the hole structural feature amplifies and concentrates strain. Thus, further application for a strain-sensing device is feasible.

Proprioceptive sensing system for therapy assessment using textile-based biomedical Micro Electro Mechanical System (MEMS)

Continued demands for better control of the operating conditions used in human motion tracking and medical applications have led to the need for better means of detecting different types of proprioceptive activity pattern. One way to satisfy this need is to use MEMS technology to develop a sensor which can be used later in the rehabilitation treatment of patients and activity monitoring. The purpose of this paper is to provide an overview of the development of textile-based proprioceptive sensor for applications in medical system and therapy assessment by Micro Electro Mechanical Systems (MEMS) technologies. To demonstrate the application of this sensor, a system has been developed in order to detect different finger flexion movements generated on a finger joint. In addition, this paper also describes an ideal design procedure for the development of MEMS proprioceptive sensor fabricated using a cloth as the structural material. Cloth is chosen as the structural material because it is inexpensive, simple to fabricate, readily available for mass production, lightweight and can be fitted onto any arbitrary surface. The cloth is stamped with silver nanoparticles (AgNPs) ink to form conductive pattern. The working principle of this textile-based sensor is based on piezoresistivity effect generated by AgNPs on a cloth substrate. Based on this fact, this sensor can give sensing information about different finger flexure movements according to the resistance change of the AgNPs. This sensor can be used as a rehabilitation device, e.g. data glove or even a communication device for the disabled to control appliances, e.g. computer keyboards.

Fly's proprioception-inspired micromachined strain-sensing structure: idea, design, modeling and simulation, and comparison with experimental results

A new strain-sensing structure inspired from insects (especially the Fly) propricoception sensor is devised. The campaniform sensillum is a strain-sensing microstructure with very high sensitivity despite its small dimension (diameter ~10Pm in a relatively stiff material of insects exocuticle (E = ~10 9 Pa). Previous work shows that the high sensitivity of this structure towards strain is due to its membrane-in-recess- and strain- concentrating-hole- features. Based on this inspiration, we built similar structure using silicon micromachining technology. Then a simple characterisation setup was devised. Here, we present briefly, finite-element modeling and simulation based on this actual sample preparation for the characterisation. As comparison and also to understand mechanical features responsible for the strain-sensitivity, we performed the modeling on different mechanical structures: bulk chunk, blind-hole, thorugh-hole, surface membrane, and membrane-in-recess. The actual experimental characterisation was performed previously using optical technique to membrane- in-recess micromachined Si structure. The FEM simulation results confirm that the bending stress and strain are concentrated in the hole-vicinity. The membrane inside the hole acts as displacement transducer. The FEM is in conformity with previous analytical results, as well as the optical characterisation result. The end goal is to build a new type MEMS strain sensor.

Batik-inspired wax patterning for cloth-based microfluidic device

This paper describes a new technique of fabricating low-cost and flexible microfluidic device for point of care diagnostics in remote region or developing countries. The technique is inspired from a traditional and ancient textile dye-resist technique, namely batik. In batik technique, wax is used to protect regions of textile material from the colouring dye(s). Similarly, we modify the wax content in cloth for defining hydrophilic channel for controlling fludic flow at micro liter volume level. Separate fluids can be dropped at different sites, and flown into a reaction site for inducing diffusion-induced mixing. As a comparison, we also fabricated cloth microfluidic device using a technique similar to that proposed by previous researchers to build 3-dimensional (3D) paper-based microfluidic device. The device made using our proposed technique can give clearer colour change display due to the mixing of different dyes. Such device could serve as a low-cost analytical device based on colorimetric (colour change) assay.

Simultaneous multiple assays on microfluidic cloth-based analytical devices

This paper describes a new class of point-of-care (POC) diagnostic devices for quantifying multiple assays by fabricating microfluidic devices on cotton cloth. This kind of microfluidic systems is appropriate for colorimetric assays that are low-cost, portable and simple to fabricate and to operate. Hydrophilic channels with hydrophobic barriers can be created using wax-resist patterning technique on cotton cloth fabric inspired from traditional batik technique. Using capillary force, the porosity of woven fabric and threads can wick micro volumes of aqueous samples from sample inlet into reaction zones across the hydrophilic channels for the mixing of their contents. These devices can be designed to perform single and multiple colorimetric assays of body fluids. The result can be observed by unaided human eye or by using digital camera and image analysis software.