Characterization of skin penetration efficacy by Au-coated Si microneedle array electrode

Ren

et al. 2016

Sensors

Micro-needle electrodes (MEs) have attracted more and more attention for monitoring physiological electrical signals, including electrode-skin interface impedance (EII), electromyography (EMG) and electrocardiography (ECG) recording. A magnetization-induced self-assembling method (MSM) was developed to fabricate a microneedle array (MA). A MA coated with Ti/Au film was assembled as a ME. The fracture and insertion properties of ME were tested by experiments. The bio-signal recording performance of the ME was measured and compared with a typical commercial wet electrode (Ag/AgCl electrode). The results show that the MA self-assembled from the magnetic droplet array under the sum of gravitational surface tension and magnetic potential energies. The ME had good toughness and could easily pierce rabbit skin without being broken or buckling. When the compression force applied on the ME was larger than 2 N, ME could stably record EII, which was a lower value than that measured by Ag/AgCl electrodes. EMG signals collected by ME varied along with the contraction of biceps brachii muscle. ME could record static ECG signals with a larger amplitude and dynamic ECG signals with more distinguishable features in comparison with a Ag/AgCl electrode, therefore, ME is an alternative electrode for bio-signal monitoring in some specific situations.

Section: Resultsmentioning

confidence: 99%

“…ME should penetrate through the stratum corneum layer and eliminate the impedance of the dead skin to collect bio-signals [ 24 ]. Therefore, the insertion process of ME needs be further studied.…”

Section: Methodsmentioning

confidence: 99%

Fabrication of Micro-Needle Electrodes for Bio-Signal Recording by a Magnetization-Induced Self-Assembly Method

Ren

et al. 2016

Sensors

“…LDW is a promising process for the easy fabrication of conductive patterns due to it being high resolution, maskless, low-cost and easy to manipulate. Various methods have been employed to fabricate microneedle arrays, including etching and lithography [ 4 , 21 , 22 , 23 , 24 , 25 ], laser machining [ 26 , 27 , 28 ], micro-molding [ 29 , 30 , 31 ], 3D printing [ 32 ], thermal drawing [ 33 ], and magnetization-induced self-assembly [ 34 , 35 ], but most of microneedle arrays were fabricated on the rigid substrates. These techniques cannot directly fabricate microneedle arrays on a flexible substrate.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Flexible Microneedle Array Electrodes for Wearable Bio-Signal Recording

Ren

Gao

et al. 2018

Sensors

Laser-direct writing (LDW) and magneto-rheological drawing lithography (MRDL) have been proposed for the fabrication of a flexible microneedle array electrode (MAE) for wearable bio-signal monitoring. Conductive patterns were directly written onto the flexible polyethylene terephthalate (PET) substrate by LDW. The microneedle array was rapidly drawn and formed from the droplets of curable magnetorheological fluid with the assistance of an external magnetic field by MRDL. A flexible MAE can maintain a stable contact interface with curved human skin due to the flexibility of the PET substrate. Compared with Ag/AgCl electrodes and flexible dry electrodes (FDE), the electrode–skin interface impedance of flexible MAE was the minimum even after a 50-cycle bending test. Flexible MAE can record electromyography (EMG), electroencephalography (EEG) and static electrocardiography (ECG) signals with good fidelity. The main features of the dynamic ECG signal recorded by flexible MAE are the most distinguishable with the least moving artifacts. Flexible MAE is an attractive candidate electrode for wearable bio-signal monitoring.

“…Experimental analysis by insertion tests have been performed to characterize the potential in vivo behaviors and sustainability of microneedles [ 1 , 3 , 11 , 15 , 16 , 17 , 23 , 32 , 34 , 39 , 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. In this section, we will summarize the experimental analysis of mechanical strength and fluid flow in in-plane Si microneedles.…”

Section: Discussionmentioning

confidence: 99%

In-Plane Si Microneedles: Fabrication, Characterization, Modeling and Applications

Mamun

Zhao

2022

Micromachines

Microneedles are getting more and more attention in research and commercialization since their advancement in the 1990s due to the advantages over traditional hypodermic needles such as minimum invasiveness, low material and fabrication cost, and precise needle geometry control, etc. The design and fabrication of microneedles depend on various factors such as the type of materials used, fabrication planes and techniques, needle structures, etc. In the past years, in-plane and out-of-plane microneedle technologies made by silicon (Si), polymer, metal, and other materials have been developed for numerous biomedical applications including drug delivery, sample collections, medical diagnostics, and bio-sensing. Among these microneedle technologies, in-plane Si microneedles excel by the inherent properties of Si such as mechanical strength, wear resistance, biocompatibility, and structural advantages of in-plane configuration such as a wide range of length, readiness of integration with other supporting components, and complementary metal-oxide-semiconductor (CMOS) compatible fabrication. This article aims to provide a review of in-plane Si microneedles with a focus on fabrication techniques, theoretical and numerical analysis, experimental characterization of structural and fluidic behaviors, major applications, potential challenges, and future prospects.