Distributed implantation of a flexible microelectrode array for neural recording.

Flexible multichannel electrode arrays (fMEAs) with multiple filaments can be flexibly implanted in various patterns. It is necessary to develop a method for implanting the fMEA in different locations and at various depths based on the recording demands. This study proposed a strategy for reducing the microelectrode volume with integrated packaging. An implantation system was developed specifically for semiautomatic distributed implantation. The feasibility and convenience of the fMEA and implantation platform were verified in rodents. The acute and chronic recording results provied the effectiveness of the packaging and implantation methods. These methods could provide a novel strategy for developing fMEAs with more filaments and recording sites to measure functional interactions across multiple brain regions.

Rewritable PEDOT Film Based on Water-Writing and Electroerasing.

Rewritable paper has greatly promoted the sustainable development of society. However, the hydrophilicity/lipophilicity of the poly(3,4-ethylenedioxythiophene) (PEDOT) film limits its application as the rewritable paper. Herein, we constructed a repeatable writing/erasing pattern on a PEDOT film (rewritable PEDOT paper) by combining wettability control, water-induced dedoping, and an electrochemical redox reaction. The treatment with a medium-polarity/high-volatility solvent (MP/HVS) adjusted the wettability of the PEDOT film (water contact angle increased from 6.5° to 146.2°), contributing to the formation of a hydrophobic writable substrate. The treatment with a high-polarity solvent (HPS) induced the dedoping of anions in the PEDOT chain, resulting in the film's color changed from blue to purple and serving as a writing process. The intrinsic electrochemical redox (elimination of color change by doping/dedoping of lithium ions in the PEDOT chain) of the PEDOT film enabled the erasing process. This writing/erasing process can be repeated at least 10 times. The patterned PEDOT film maintained excellent stability to standing diverse solvents (low-polarity solvent (LPS) and MP/HVS), high temperatures (350 °C), and irradiation of different light wavelengths (wavelengths of 365, 380, 460, 520, and 645 nm). Additionally, the conductivity of the PEDOT film was quantitatively measured (impedance: LPS, increased 8.84%; MP/HVS, decreased 6.67%; and HPS, increased 27.97%) by fabricating a micropatterned PEDOT electrode. This work will provide a method for the fabrication of PEDOT-based optoelectronic functional materials.

Application of graphene nanowalls in an intraocular pressure sensor.

As the second leading cause of blindness in the world, glaucoma is mainly caused by persistent high intraocular pressure (IOP) that compresses the optic nerve and causes permanent damage. Noninvasive continuous monitoring of IOP is an essential method for the diagnosis and treatment of glaucoma. In this paper, we propose a new strain gauge material based on graphene nanowalls (GNWs) for continuous monitoring of IOP with high sensitivity in a wide range. By simulation, we studied the relationship between the strain of the cornea and contact lens and IOP. The structure and the location of the GNWs in the contact lens are optimized. A method for transferring GNWs on contact lenses with the assistance of a gold film is proposed. The simulated tests on porcine eyes in vitro show that the resistance response of the device to normal IOP fluctuation reaches 1.014 kΩ mmHg-1. Its normal sensitivity of 42 250 ppm mmHg-1 and the response range of 0-75 mmHg are far more than those of most noninvasive methods reported before. This study shows the enormous potential of GNWs for continuous IOP monitoring with high sensitivity and low power consumption.

An experimental study on the digital precision of internal fixation via the sinus tarsi approach for calcaneal fractures.

OBJECTIVE: To investigate the effectiveness and accuracy of internal fixation of calcaneal fractures with a three-dimensional (3-D) printing navigation module via the sinus approach. METHODS: Eleven lateral lower extremity specimens were used in the experiment and divided into the digital design (DD) group ( n = 11) and the real surgery (RS) group ( n = 11). For the DD group, thin-section computed tomography (CT) scans, virtual fracture modeling, virtual bone plate fixation, sinus occlusal module design, and navigation module design were performed for the cadaver specimens. A 3-D navigation module was printed using a 3-D printer. For the RS group, the sinus approach incision was made, and the navigation module was used to assist the placement of screw fixation and anatomically locked bone plate fixation. Thin-layer CT scans, 3-D reconstructions, and reconstruction of the nail paths were performed in the RS group and 3-D registered with the DD group. 3-D coordinate values for the screw entry and exit points in the RS and DD groups were recorded, and the corresponding offset values of the screw points were calculated. The number of qualified nails at different accuracy levels was counted. The χ2 test was used to compare the data for the DD and RS groups to obtain the accuracy level for both groups when p > 0.05, which is the critical value for experimental accuracy. RESULTS: A total of 11 bone plates were placed and 120 screws were locked. None of them protruded from the inferior articular surface. The screw entry and exit point offsets were 1.71 ± 0.11 mm and 3.10 ± 0.19 mm, respectively. When the accuracy requirement for the entry point was 3.8 mm, there was no statistically significant difference between the two groups ( p > 0.05). Similarly, the accuracy of the exit point of the screw could only reach 6.6 mm. CONCLUSION: Internal fixation of calcaneal fractures via the sinus tarsi approach with an anatomical locking plate based on the 3-D printing navigation module can achieve accurate screw placement and good overall internal fixation.

Anatomical reduction and precise internal fixation of intra-articular fractures of the distal radius with virtual X-ray and 3D printing.

To evaluate and precisely internal fix intra-articular distal radial fracture (IDRF) using the virtual X-ray and three-dimensional (3D) printing technologies. Twenty-one patients with IDRF were recruited, and the data from digital design group (DDG) and real surgery group (RSG) were collected and analyzed. In DDG, the data from thin-slice computed tomography scan, virtual X-ray measurement parameters, including volar tilt, palmar tilt, radius length (D1), ulnar variation (D2), locking plate position parameter (D3) and distance between key nail and joint surface (D4) were collected. The bone was virtually fixed with the locking plate, and the final model of radius with the screw was obtained by 3D printing. In RSG, the locking plate was precisely pre-bended and used in surgery. During the surgery, the key K-wire was accurately placed and the locking plate was adjusted with the aid of the U-shaped navigation arm. The C-arm was used to observe the positions of key K-wires and the locking plate, and the same above-mentioned parameters were measured intra- and post-operatively. The data from RSG and DDG were compared statistically by t test. This approach proved to be successful in all 21 patients, and none of the screws pierced through the wrist joint surface. All the measured parameters, including the volar tilt, palmar tilt, D1-4, in RSG were not significantly different from preoperative DDG data. Virtual X-ray measurement of anatomical reduction parameters and 3D printing can help the anatomical reduction and precise internal fixation by providing quantitative references, preoperatively, intraoperatively and postoperatively.