Printable, multifunctional, flexible, health monitoring detachable patch sheets with human motion detection capability.

Because a wearable device comprised of a flexible film should be comfortable to wear over the skin, several reports have focused on the film thickness to prepare ultrathin films that are a few micrometers or nanometers thick. [26,27] Thinning a film to this scale should realize a film capable of covering the skin asperity conformally, resulting in a good comfort while wearing and a relatively strong adhesion on skin without glue. However, ultrathin films can be difficult to handle and attach to skin. Additionally, assembling other components such as a signal processing circuit and battery without sacrificing the advantage of thickness remains challenging. Thus, many reports still employ both ultrathin film flexible devices and relatively thick films (several hundred micrometers). [1,[4][5][6][7]9,12,16,18,19,22,28] However, the effect of film thickness on sensing has yet to be discussed, although a systematical study is important to realize precise health data recordings. In addition to the wearability and film thickness depedences, biocompatibility of the sensor and film materials is another important parameter to consider for the practical application as a wearable device.In this study, we explore the dependence of the temperature change, which is measured by a printed temperature sensor fabricated on polyethylene terephthalate (PET), on thickness. A thick film was selected due to handling ease and ability to integrate other components in the future. However, some sensors such as an ECG sensor must attach onto skin with good adhesion without sacrificing conductivity, and a relatively thick flexible film itself cannot attach to skin without an adhesion layer. To create good adhesion between an ECG sensor and skin without losing conductivity, a high adhesive conductive polymer onto skin is also developed. Although gel-based electrodes are often used in medical applications, gel-based electrodes are unsuited for long-time measurements due to skin irritation. [15] Thus, we developed a gel-less sticky electrode using biocompatible materials by characterizing the adhesion, impedance between skin and the ECG sensor, and repeatability for use. Finally, as a proofof-concept demonstration, simultaneous efficient skin temperature and ECG signal recordings were conducted using a conductive polymer with an optimized film thickness. Figure 1a describes an integrated device image with a temperature sensor, an ECG sensor, an equivalent circuit between Wearable, flexible healthcare devices, which can monitor health data to predict and diagnose disease in advance, benefit society. Toward this future, various flexible and stretchable sensors as well as other components are demonstrated by arranging materials, structures, and processes. Although there are many sensor demonstrations, the fundamental characteristics such as the dependence of a temperature sensor on film thickness and the impact of adhesive for an electrocardiogram (ECG) sensor are yet to be explored in detail. In this study, the effect of film thickness for skin te...

Using a flattened SiO2/Cu electrode/36–48° LiTaO3 structure, a small (5×5 mm2) surface acoustic wave (SAW) duplexer with a good temperature coefficient of frequency (TCF) for US personal communication services (PCS) was realized by the authors. However, a smaller duplexer is strongly required. Using the flip-chip bonding process of SAW chips and a Rayleigh SAW propagating on a flattened SiO2/Cu electrode/126–128° YX-LiNbO3 structure, which has a larger coupling factor than the above-mentioned substrate, a smaller (3×2.5 mm2) SAW duplexer with a good TCF was realized.

Flexible healthcare devices attract much research attention due to their potential application in everyday health monitoring and data acquisition. In order to precisely monitor changes in health data, simultaneous recording of motion data is of vital importance, as different modes of human activity have a strong influence on a person's vital signs. However, human motion detection has received comparatively little attention in flexible electronics, even though flexible health monitoring sensors are well‐studied and researched by many groups. In this study, a planar‐type, multifunctional health sensor sheet integrated with acceleration, temperature, and electrocardiogram sensors, fabricated completely by printing methods is proposed and demonstrated. A vibrational space for the acceleration sensor is created by using a kirigami structure for the electrodes, allowing it to be pushed out of plane without affecting the resistance. The acceleration sensor's sensitivity is investigated experimentally by changing the dimensions of its beam structure, after which we are able to optimize the sensor such that it would be able to detect light human activity. Finally, as a proof of concept, the device is successfully demonstrated to be able to detect human motion, skin temperature, and electrocardiogram signals simultaneously when attached to the chest of a test subject.

In this paper, we report a new structure of a shear horizontal (SH) type boundary acoustic wave for cellular phone applications. Such a structure composed of electrodes with a low shear wave velocity between two materials, namely, the SiO 2 film/Au-electrode/LiNbO 3 substrate, is proposed. The ladder filter used in this paper had this structure. By changing the propagation angle of the acoustic wave, the electromechanical coupling factor k 2 range from 0 to 16% was obtained, as well as a normalized bandwidth range 0.67 to 1.85 fold as large as that of a 36 -46 Y-X LiTaO 3 leaky surface acoustic wave (LT-LSAW) filter. In addition, an excellent temperature coefficient of delay time (TCD ¼ 25 ppm/ C) and a large mutual coupling coefficient 12 (¼ 0:15) were also obtained.