a strain-absorbing design for tissue–machine interfaces using a tunable adhesive gel
In order to measure the physiological signals of the human body, it is essential to establish stable, mild and non-allergic contact between the target biological tissue and the electric probe. However, it is difficult to form a stable interface between the two for a long time, especially when the surface of the biological tissue is wet and/or the tissue exhibits movement. Here we design and manufacture intelligence, pressure- Absorbing electronic devices that can be attached to wet and complex tissue surfaces and allow reliable, long-lasting Term measurement of life signals. We show a multi-electrode array that can be attached to the surface of the rat heart, resulting in a good guaranteed angular contact over 3 u2009 h. In addition, we have demonstrated a highly sensitive, stretchable array of strain sensors using similar designs. Ultra- Flexible electronic devices with enhanced adhesion to tissues can implement future applications in chronic in vivo monitoring of biological signals. Modified wheels (1u2009g)(AOI-E2- APR100 advanced soft material company) Suspended in distilled water (10u2009ml, 40u2009°C) Stir until completely dissolved. Next, the light initiator (0. 2u2009g)4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone ( Ciba special chemicals company Irgacure 2959) Add the solution under constant stirring to obtain a uniform mixture. Finally, PVA (0. 1, 0. 2, 0. 3, 0. 4 or 0. 5u2009g)( Kuraray, M: 87,000-127,000; Degree of hydrolysis: 87-89%) Add in the solution and stir the solution for 10 µh to ensure its uniformity. The prepared solution is poured on the equipment treated with oxygen plasma (300u2009W, 30u2009s) Covered with glass. The gel thickness is controlled by the spacer between the device and the glass and is patterned by covering the glass with a metal mask. Finally, the solution is cross-cutting. Connected by ultraviolet radiation ( Optical module of Ushio) With 1 min 250 W and 365 nm. A test gel strip was prepared with a silicone rubber mold with a thickness of 2mm and a width of 1. The middle of 5mm (see inset of ). Measurement of Young\'s modulus of the gel strip using Shimadzu\'s dynamic mechanical analyzer (Ag-X). The gel strips stretch at a constant rate of 4 mm/min. A PDMS layer (1u2009mm) Used as a support layer for 1. 4-μm- Too thick pet (PET)foil (Mylar 1. 4 Pütz GMBH Co. CW02). Next, Au (20u2009nm) It was deposited on PET film. Then the PET film is made in shape-preserving contact with the gel strip fixed on the glass substrate; The contact area is 1 cm. The film is then stretched using a dynamic mechanical analyzer with a constant rate of 4mm min to measure the shear stress (). Use double-secure a piece of commercial pork shoulder muscle on a glass substrate Double sided tape. The gel patterned on the PET film is in contact with the shape preservation of the pig tissue; The contact area is 1 cm. Then shoot the film at the same speed, that is, 4 minutes. During the measurement process, the surface of the pig tissue remains moist enough to prevent drying. In the case of 90 ° stripping- In addition to the measurement, the prepared Au film is in contact with a gel strip bent into a 90 ° angle. The supporting silicone rubber layer in the contact area was removed to minimize the residual stress generated by the bending. Then, laminate the Au film in the same way (). The impedance of rotaxane and pva glue was measured using a metal-insulator-metal structure and an-parameter analyzer (Agilent, 4156C) As a function of frequency (20 to 10u2009Hz). A 1-mm- The thick ion gel layer is sandwiched in an Au- Pi substrate deposited; the top- The contact area is 1 cm. Repeat measurement for AC voltage of 5-1,000. The Au electrode and the interconnect array are deposited together. supported 1. 4-μm- Thick PET foil using a hot evaporator. A thin layer (1u2009μm)of parylene (diX-SR, junior Society) Then deposited on the structure by chemical vapor deposition (CVD) Isolate the entire structure except the electrode area. For UV mapping of the gel, pour the gel solution onto the substrate. Use slide tape spacers to disperse the solution at a distance of about 70 μm from the substrate. Use a shadow mask to expose the electrode area to UV radiation for 1 minute. By immersing the substrate in water, the remaining solution on the unexposed area is removed. The electrode is connected to the amplifier (MEB- 9104, Nihonkohden. ) ECG signals in the heart of rats were monitored. The research programme for the use of rats follows the Tokyo University\'s regulations on animal care and use, which are approved by the Institute of Medicine\'s committee on animal experiments, the University of Tokyo. We used 10-week-old rats. The rats were placed under general anesthesia with isofluoride; Put the anesthesia tube into the trachea. During the procedure, we used the commonly used technique of operation management. Keep your body temperature at 37 °c using a heating pad. To approach the surface of the heart, we open the chest with a median incision. Separate the breastbone with a rib hanger. Obtaining an MRI scan using TurboRARE method. A 7-T MRI system ( Bruker Co. BioSpec 70/20 USR) It was hired for this purpose. To ensure that the pva tape is observed in the MRIs scan, the acquisition parameters are adjusted to the following T2- Weighted level: repeat time () 2,500 u2009 ms and echo time ()of 33u2009ms. The original position of the gel strip is marked on the skin. Ag flakes ( Sigma Aldrich 2g); A fluorine-substituted polymer with partial fluorine- Four fluorine Six fluorine propylene ,(0. 5 Daig Daiel-gold industry-G912); Ionic liquid, 1-ethyl-3- Trifluoride ether (0. 05u2009g); And graphene ink ( Written by Jokoh, Japan)(0. 2 u2009 g, scattered in 4-methyl-2- At 10 mpa more than 10 times, get 10 wt % pentanone by jet milling) Mix in 4-16 Thanhmethyl-2-pentanone (1. 5u2009g). Paste the result- Then, the thickness and width are ~ A thin silicone rubber substrate of 10 and 1,500 μm is printed with similar ink. Then, a 2-μm- In addition to the area where the transistor matrix and wires are connected, a thick layer of silicone rubber is covered on the ink pattern. The bottom of the silicone rubber layer was treated with oxygen plasma (300u2009W, 30u2009s) And a layer of pva glue ( 10mm x 1mm, thick to 30 mu m) The pattern is OK. An active matrix of organic transistors is made on a 1. 4-μm- Thick PET film supported by polymer layer. First, a 20-nm- The thick Au layer is deposited on the substrate as a text line. Then, a 200-nm- Thick parylene layers are formed by CVD. Next, a 30-nm-thick DNTT (dinaphtho[2,3-b:2\',3\'-f]thieno[3,2-b]thiophene) An organic active layer is deposited using a shadow cover evaporation. After that, a 50-nm- Thick Au layers are deposited using shadow shielding to form source and drain and interconnect. Package by CVD deposition of Parylene. A hole was drilled inside with a laser. Finally, Au is deposited on the pad to connect it to the gel electrode. Active Matrix of low level The voltage motion sensor has different structures. First, a 20-nm- Thick aluminum (Al) The layer evaporates on 1 as a text line. 4-μm-thick PET film. Then, a 4-nm- Thickness of alumina (AlO) By treating the Al layer with an oxygen plasma, it is formed on the Al layer (300u2009W, 5u2009min). Layer AlO is 2-nm-thick self- Assembly single layer (SAM) By immersing the substrate in 2- 5-mM n containing n-alcohol- 14 P. phosphate at room temperature of 16 h. The capacitance of the gate medium is large (700u2009nFu2009cm) Small leakage current. The following process after the gate insulator is the same as the above active matrix manufacturing method. The printed conductor is integrated with the matrix while pre- Stretched 25%. All electrical measurements are performed in the air using a semiconductor parameter analyzer (4156C, Agilent).