The Development of a Blood Leakage Monitoring ... - IEEE Xplore

IEEE SENSORS JOURNAL, VOL. 15, NO. 3, MARCH 2015

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The Development of a Blood Leakage Monitoring System for the Applications in Hemodialysis Therapy Ho-Chiao Chuang, Chen-Yu Shih, Chin-Hui Chou, Jung-Tang Huang, and Chih-Jen Wu Abstract— The purpose of this paper is to design, fabricate, and characterize of a bracelet monitoring device for blood leakage detection during the hemodialysis treatment. The design includes a photointerrupter, a Bluetooth 4 wireless module, power, and alert components. The validation results show that it only needs a very small amount of blood (0.01 ml), and takes 1.6 s to detect a blood leakage. Furthermore, the lifetime of the battery on this device is longer than the currently available commercial products. It can continuously give out an alert for 18-h long and continuously monitor up to 41 h. In addition, the transmission range of Bluetooth wireless signal can be extended to 23 m. As long as the patients wear this bracelet blood leakage detector during the hemodialysis therapy and affix the absorbent material onto the junction of fistula, any blood leakage can be detected. As the absorbent material is placed at the light sensing position of the photointerrupter, which causes the received light intensity to change during blood leakage. Once a blood leakage occurs, the absorbent material absorbs the blood due to the capillary action and triggers the alarm system. A warning light will also be activated, and a leakage occurrence is transmitted to the healthcare stations alarming healthcare workers via the Bluetooth wireless. The healthcare workers can take appropriate action immediately to prevent any risks to the patients during hemodialysis therapy. The proposed blood leakage monitoring system can improve the current medical approach for the hemodialysis therapy. Index Terms— Hemodialysis, blood leakage detection, photointerrupter, Bluetooth 4.0.

I. I NTRODUCTION

A

CCORDING to the annual data report of 2013USRDS (United States Renal Data System), it indicates that the reported rates of incident end stage renal disease (ESRD) across the globe noticed an important trend. In 2011, the top three countries with the highest rates of reported incident ESRD are Jalisco (Mexico), United States and Taiwan. Furthermore, the top three countries with the highest rates

Manuscript received August 7, 2014; accepted October 16, 2014. Date of publication October 22, 2014; date of current version December 18, 2014. This work was supported by the National Taipei University of Technology and Mackay Memorial Hospital under Contract NTUT-MMH-10116. The associate editor coordinating the review of this paper and approving it for publication was Prof. Aime Lay-Ekuakille. H.-C. Chuang, C.-Y. Shih, C.-H. Chou, and J.-T. Huang are with the Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan (e-mail: [email protected]; [email protected]; [email protected]; [email protected]). C.-J. Wu is with the Division of Nephrology, Mackay Medical College, Mackay Memorial Hospital and Medicine, Taipei 10449, Taiwan, and also with the Department of Pharmacology, College of Medicine, Graduate Institute of Medical Sciences, Taipei Medical University, Taipei 11042, Taiwan (e-mail: [email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/JSEN.2014.2364302

of reported prevalent ESRD in 2011are Taiwan, Japan and United States. Hemodialysis therapy continues to be the most common method of treating ESRD worldwide. Data shows that in over 76 percent of reporting countries, at least 80 percent of patients are on this therapy method [1]. In addition, it also reports that more than 90% of dialysis patients in the United States are on hemodialysis therapy [2]. Venous needle dislodgement has been reported to be a potentially serious complication during the hemodialysis therapy. In 2012, the American Nephrology Nurses’ Association (ANNA) carried out an investigation on the venous needle dislodgement. The survey results revealed that 76.6% (n = 894) of the 1166 participants indicated about their observances of venous needle dislodgement in the past five years, and with 8.2% (n = 96) of those having seen five events or more in this time period. Moreover, slightly more than half (57.9%) of the 1166 participants pointed out that venous needle dislodgement occurs very often or often. An additional 23.1% rated their concern as occasional [3]. From the above reported data, it shows a high frequency of occurrence on venous needle dislodgement, and indicates that the venous needle dislodgement is indeed a potential problem during hemodialysis therapy. A commercial blood leakage detector, HEMOdialert products [4], specific for hemodialysis therapy is currently available, which requires the sensing sensitivity of less than 1 ml of blood, and the blood leaking condition can be detected in 1 ∼ 2 seconds. The sensing method is basically based on the changes of the voltage signal in the sensor. This device includes a detector having two spaced apart electrodes, each electrode is connected to a signal generating source via a lead. The device also includes a signal processing unit that detects a change of state across the electrodes produced by the introduction of a fluid and an alarm actuated by the change of state. The electrodes are encased in a flexible nonconductive material and can be reused after cleaning [5]. The other commercial product for the detection of blood leakage is available from Redsense [6] with a sensing sensitivity of approximately 1 ml of blood. The detection of a blood leakage is by a change in electrical conductance in a circuit, which comprises two metal wires separated by a slit. When the blood flows into the slit, it creates an electrical connection between the two wires, and thus, the blood leakage can be detected [7]. This product is a disposable blood leakage device, which cannot be reused. Ahlmén et al [8] reported a study on the venous needle dislodgement during the hemodialysis therapy by using a

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Redsense blood leakage detector. The studies have been performed by 2 dialysis nurses at each of 5 dialysis departments. A total of 213 test dialyses were performed and two hundred test dialyses were studied, after excluding of 13 tests. The nurses indicated that the safety of the hemodialysis therapy has been improved significantly when using a new safety device, blood leakage detector. Ramesh Wariar et al [9] filed a patent on the needle dislodgement detection. A leakage of blood can be detected by a change in capacitance detection via a capacitive sensor. When the patient’s needle dislodgement occurs, the change in the wetness by the introduction of a blood can be detected by using this sensor. Lay-Ekuakille et al [10], [11] reported that the pressure variations produced by blood flow is similar to those produced by leakage in pipelines and thus, the vibrations produced by blood pressure within the artery or vein could be used for the leakage detection. The products outlined all need 1 ∼ 2 ml of blood to trigger the blood leakage detector due to their sensor design. However, the amount of blood needed for sensing blood leakage can be improved. In addition, the price of such products is not affordable for general patients, and thus cannot be popularized. Although these products have an alarm, the loudness of the alert is limited by the distance, causing healthcare workers to give more attention to whether the alarm is warned or not, which is an inconvenience. In this study, a photointerrupter is used as a sensor for detecting the blood leakage and combined with a Bluetooth 4.0 [12] for the function of wireless transmission. Furthermore, through our circuit design, the blood leakage detector can be integrated on a bracelet, which is a simple and inexpensive way to monitor the leakage of blood during the hemodialysis treatment. If the detector senses a leakage of blood, the alert system will be activated immediately, such as sound and a warning light. In addition, an alert signal will be transmitted to the healthcare station via the wireless transmission as well, so that healthcare workers can immediately take appropriate action to prevent any risks from happening. II. D EVELOPMENT OF B LOOD L EAKAGE D ETECTOR A. Architecture of Blood Leakage Detector In this study, the development of blood leakage monitoring system is divided into two parts. One is the hardware: a bracelet monitoring device for blood leakage detection (hereinafter referred to as “blood leakage detector”) and the other is the software: the user operating interface on the monitoring computer (hereinafter referred to as “user interface software”). Our blood leakage detector is designed for the purpose of easy operation, small size, light weight, low amount of blood for detection, high sensitivity, low cost and long battery life. The sensing element on the detector is a photointerrupter and with an absorbent material used for adsorbing the leaking blood. The working principle is to place an absorbent material at the sensing region. When the colored liquid (red ink representing actual blood) drops at the edge of absorbent material, the absorbent material adsorbs the red ink due to the capillarity

action. At this point the red ink quickly covers the entire absorbent material which makes a change in light penetration. The photointerrupter sensing element adjacent to the absorbent material will sense the light changes and the original voltage signal of the photointerrupter alters accordingly. This changed voltage signal is sent to alert components and the Bluetooth module simultaneously via the circuit within the detector. The signals are then transmitted to the monitoring computers at the health care stations via the Firmware code within the Bluetooth wireless chip. The monitoring computer is equipped with a Bluetooth 4.0 receiver and installed with a Bluetooth software to receive signals sent from the blood leakage detector. Hence, the received signals are recorded with the sensing information from the blood leakage detector. In this study, different types of absorbent materials were used in the relevant sensing experiments and the results were observed and analyzed for the selection of proper absorbent materials used for the blood leakage detector. Meanwhile, the design iterations were carried out to optimize the hardware specifications of the detector. After the development and preliminary validation of the proposed blood leakage detector, the simulated hemodialysis treatment situations was performed to verify the connection between the user interface software and blood leakage detector; in order to prove the proposed blood leakage detector is a substantial improvement on the hemodialysis treatment. B. Blood Leakage Detector Components 1) Photointerrupter: Photointerrupter is an optical coupling (OC) element which is electrically insulated and optically coupled to each other in the light emitting and receiving parts. The principle is to convert the input electrical signals into light, meaning the light-emitting unit (emitter) emits an infrared light. The light receiving unit (collector) receives the infrared light and converts it into electrical signals so that the light emitting portion and light receiving portion of the photointerrupter becomes conducted. A model of TCST110 photointerrupter is used in this study for sensing the blood leakage. When the emitted infrared light is blocked by the absorbent material, the emitter on the photointerrupter does not conduct to the collector (i.e., open circuit). At this point, the received voltage on the collector becomes Lo and changes to Hi while the absorbent material being removed which conducts the light emitting and receiving parts. Thus, the conduction between the emitter and collector can be detected by examining the signal, Hi or Lo. The schematic diagram of a photointerrupter is shown in Figure 1. 2) Bluetooth Module: In this study, a Bluetooth chip CC2540 (Texas Instrument (TI), 2.4 GHz Bluetooth Low Energy System-On-Chip) is adopted as the wireless transmission function of the detector [13]. This chip conforms to the Bluetooth v4.0 compliant and offers low power consumption, quick setup, small size and other characteristics, which has been widely applied in various fields. The entire circuit except the Bluetooth chip is developed in house based on an architecture design of the system on Chip (SOC), including the 8051 compatible microcontroller core and Bluetooth. The

CHUANG et al.: DEVELOPMENT OF A BLOOD LEAKAGE MONITORING SYSTEM

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Fig. 2.

Schematic diagram of the circuit design.

Fig. 3.

Photograph of the blood leakage detector.

Fig. 1. Schematic drawing of the Photointerrupter. (A) Without the absorbent material. (B) With the absorbent material.

Bluetooth module with a size of 18 × 11 mm is consisted of the Surface Mounted Devices (SMD) electronics mounted on a double-sided printed circuit layout and a Bluetooth chip. The flash memory is built in the Bluetooth chip CC2540 which supports the firmware of the device for instant upgrade, and stores the data in the chip to enhance the design flexibility. In addition, its function still contains a low-power RF IC, a fully embedded protocol stack for Single-Mode, a profile software and applications support, etc. Moreover, the excellent RF performance on the link budget can be increased to be more than +97 dB and can coexist with other 2.4 GHz devices. It is compatible with Bluetooth 4.0 standard as well. Therefore, it can be fully applied in any applications for testing, evaluation and development. 3) Alert Components: The alert components used in the blood leakage detector include the light and sound devices, providing both visual and auditory warning signs. The descriptions of the alert components are as follows. a) SMD LED: In this study, a Surface Mount Device Light-Emitting Diode (SMD LED) is used in the blood leakage detector to provide the visual warning signal. SMD LED has advantages, such as the power saving and the small volume, which saves the overall circuit space for our detector. In addition, its high specification features are more effective, long life, not easily damaged, fast response and high reliability, which is not available on the conventional light sources. b) Buzzer: An electrical buzzer generally comprises of an electromagnetic or a piezoelectric element and is widely used as an audible electronic component in many electronic products. Whereas the piezoelectric buzzer is mainly assembled by a multivibrator, a piezo ceramic element, an impedance matching device, a resonance box, and a shell. In addition, it has a smaller volume compared to the electromagnetic one and the sound is created via a vibrating metal film due to the piezoelectric effect. Thus, in this study a piezoelectric buzzer was chosen to be installed on the blood leakage detector as an auditory alert. 4) Circuit Design: In this study, the electronic components used in our proposed detector mainly include the described photointerrupter, Bluetooth module and alert components. The circuit design is based on the switch (on/off) of the

photointerrupter, meaning it depends on the light transmittance of the absorbent material. The switch signal causes the voltage change between the emitter and collector of the photointerrupter, and thus the blood leakage detection can be determined. Furthermore, the obtained voltage change value (analog signals) is sent to the alert components through an operational amplifier in the Bluetooth module and is converted into digital signals. Finally, the digital signals can be sent to a monitoring computer via Bluetooth wireless transmission, and the schematic diagram of the circuit design is shown in Figure 2. 5) Package and Wearable Device: In this study, an easy processing material, acrylic sheet, with a thickness of 1 mm is used as a case for our detector. The overall device dimensions are 52×52×22 mm. A commercially available multifunctional bandage is utilized as the bracelet where the straps can be adjusted to the proper fixture size. Finally, after processing of the bracelet, it can be bonded on the case of the blood leakage detector as shown in Figure 3. III. E XPERIMENTAL D ESIGN AND R ESULTS After the design and fabrication of the proposed blood leakage detector, a series of testing experiments are also performed such as battery life tests and Bluetooth wireless transmission distance measurements. From the experimental results, the hardware specifications of the detector can be

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Fig. 5. Photograph of experimental setup for battery life test: (A) under general monitoring state and (B) under blood leakage state.

Fig. 4. Schematic diagram of the battery life test: (A) under general monitoring state and (B) under blood leakage state.

optimized and used as the database for the future design changes. Since the sensing method of our detector is to monitor the blood adsorption of the absorbent material in the sensing region of photointerrupter, detection of blood leakage is based on the capillary action detected. The properties of the absorbent material strongly affect the sensitivity of the blood leakage detector; thus, adsorption tests are needed to be performed on different types of absorbent materials to examine adsorption time, adsorption capacity, etc. By analyzing the testing results, a suitable absorbent material can be determined. In addition, for all of the experiments performed in this study, new batteries are used to ensure that there is a sufficient power for performing each experiment. A. Battery Life Experiments The purpose of the developed detector in this study is to monitor the blood leakage detection during the hemodialysis therapy and battery life of the detector is essential. Under the simulated hemodialysis treatment, battery life tests are conducted under two states. One is enabling the detector under the general monitoring state (without blood leakage), and the other is when the detector continuously sends out the warning signals (with blood leakage). The battery life test results under both conditions are recorded. Under the general monitoring state, namely the blood leakage detector stays connected with the monitoring computer. The battery life tests are performed by placing the absorbent material at the sensing region of the photointerrupter. The diagram of the photointerrupter under general monitoring state for battery life tests is shown in Figure 4 (A) and the experimental setup is shown in Figure 5(A). The experimental results of the battery life tests are based on whether the blood leakage detector stays connected with the monitoring computer or not. If the detector disconnects with the monitoring computer, it means the battery is exhausted. Finally, the overall battery life can be summed up by adding the total connection time of the detector to the monitoring computer. Under the blood leakage state, namely the blood leakage detector activates an alarm (warning sound and lights) and continuously sends an alert signal to the monitoring computer. The battery life tests are performed by placing the absorbent

material with red ink at the sensing region of the photointerrupter. The diagram of the photointerrupter under blood leakage state for battery life tests is shown in Figure 4 (B) and the experimental setup is shown in Figure 5(B). The experimental results of the battery life tests are based on whether the blood leakage detector stays connected with the monitoring computer and continuously sends out the alert signals. If the detector disconnects with the monitoring computer or stop sending out the alert signals, it means the battery is exhausted. Finally, the overall battery life can be summed up by adding the total connection or alerts time. The experimental results of the battery life will depend on the hardware specifications and firmware setting conditions of blood leakage detector: Blood leakage detector version #1: Hardware: A general LED is used as the alert components and a 12V battery is utilized as a power source. Firmware: 1. The Bluetooth transmission mode is set to continuously send out signals under any state. 2. When the blood leakage detector links to the monitoring computer via a Bluetooth connection, the LED is always turned on under any state. Blood leakage detector version #2: Hardware: The original LED is changed to a SMD LED and the power source remains the same. Firmware: 1. The Bluetooth transmission mode is set to send out an alert signal every three seconds under leaking state. 2. When the blood leakage detector links to the monitoring computer via a Bluetooth connection, the LED is not turned on until the leaking state occurs. Blood leakage detector version #3: Hardware: The original 12V battery is changed to a 3V battery; the other parts remain the same. Firmware: The same with version #2. Blood leakage detector version #4: Hardware: According to the power specification of a 3V battery, a new type of circuit is designed and fabricated to save power. In addition, a warning buzzer is added and the regulator IC is removed. The other parts remain the same. Firmware: The same with version #2. Experimental results show that the average battery life time of version #1 and #2 under monitoring state are 12.23 and 33.15 minutes, respectively, as shown in Figure 6. The average battery life time of version #1 and #2 under


Fig. 6.

Fig. 7.

Experimental results of battery life time under monitoring state.

Experimental results of battery life time under leaking state.

leaking state are 11.56 and 25.26 minutes, respectively, as shown in Figure 7. From the experimental results of the version #1, it is clearly seen that a serious shortage of the battery power for our blood leakage detector is founded. An average battery life time of only 12.23 minutes was measured, which is still far away from the typical required time of 4 hours during the hemodialysis treatment. Thus, electronic components in the detector with higher power consumption are removed and the firmware is further modified to determine the parameters of the monitoring state and the interval time of sending signals in order to increase the battery life time. The experimental results of the version #2 indicate that the battery life time of the detector has indeed improved. However, it is still away from the goal of 4 hours and the average battery life time was measured at 33.15 minutes. After this test, the circuits of the detector are redesigned and the original battery (Duracell 23AE) is replaced with a new type Panasonic CR-123AEP, which has a nominal capacity of 1400 mA, 42 times more than the original one (33 mA). Experimental results show that the average battery life time of version #3 and #4 under monitoring state are 35.14 and 40.86 hours, respectively, as shown in Figure 8. The average battery life time of version #3 and #4 under

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Fig. 8.

Fig. 9.

Experimental results of battery life time under monitoring state.

Experimental results of battery life time under leaking state.

leaking state are 34.34 and 18.43 hours, respectively, as shown in Figure 9. From the experimental results of the version #3, it is confirmed that after the replacement of the Panasonic CR-123AEP battery, the blood leakage detector can meet the demand for electricity. As previously limited to the shortage of the battery life time, some related electronic components are not included in the detector. Now, the new designed circuits with adding a warning buzzer are implemented on the detector in order to achieve the proper functions of the blood leakage detector. According to the experimental results of the version #4, it can be found that the previous circuit is designed without considering a regulator IC for the version #3 (3V battery). Therefore, after redesigning the circuit in the version #4, the battery life time under monitoring state increases from 35.14 hours (version #3) to 41 hours, an increment of about 5 hours. The battery life time of the detector under leaking state is reduced from 34.34 hours (version #3) to 18.43 hours (version #4) due to the increased use of a warning buzzer. After a few design iterations, the battery life time of the proposed blood leakage detector is longer than the currently known commercial available products. It could continuously send out warning signals up to 18 hours under leaking state and may be up to 41 hours under monitoring state.

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TABLE I E XPERIMENTAL R ESULTS OF THE S ENSING T IME AND THE A DSORPTIVE C APACITY OF D IFFERENT A BSORBENT M ATERIALS

Fig. 10.

The measured Bluetooth wireless transmission distances.

B. Experiments on the Bluetooth Wireless Transmission Distance In this study, the main feature of our developed blood leakage detector is with a function of sending out the warning signals to the monitor computer via Bluetooth wireless transmission technology. The warning signals can be received within a certain range of distance to monitor the status of blood leakage during the hemodialysis therapy. By performing the experiments on Bluetooth wireless transmission, the effective transmission distance between the detector and the monitoring computer can be measured. Within this range, it ensures that the healthcare workers could control the patient’s condition during the hemodialysis treatment. The absorbent material is placed at the sensing region of the photointerrupter and the detector is in connection with the monitoring computer. Then the monitoring computer is placed at a fixed position and the initial distance between the detector and the monitoring computer is set to zero meter. After start of the experiments, the blood leakage detector is moved away from the monitoring computer, and the connection with the monitoring computer is observed at any time. The detector is moved further again if the connection is examined to be ok. The distance of each move is 0.77 meters until it is disconnected with the monitoring computer. The determination of the experimental results is based on the measured longest transmission distance between the detector and the monitoring computer under connection. The measured average of the longest distance of the Bluetooth wireless transmission is 23 meters as shown in Figure 10. C. Absorbent Materials Test Under the leaking state, the amount of red ink required for the absorbent material and the sensing time of the adsorptive conditions (capillarity) are important factors for the developed blood leakage detector. Thus, under the same experimental setup and parameters, different absorbent materials are each subjected to the same experiment ten times to obtain an average of the experimental results as shown in Table 1. The experimental results show that the change of the absorbent material directly affects the length of their sensing time. Whereas the changing capacity means the total adsorptive

amount of red ink after the start of the experiment until the photointerrupter senses the changes in light intensity. Adsorptive capacity is the maximum amount of red ink that absorbent material could absorb (saturation capacity); meanwhile the voltage signals of the photointerrupter are stabilized. Based on the measured initial and final voltages of the photointerrupter on different absorbent materials tests shown in Table 1, the preferred absorbent materials in this study can be determined. D. Blood Leakage Detector Test First, the simulated blood leakage tests under monitoring and leaking states on the photointerrupter are implemented. The voltage changing signals of the photointerrupter from a monitoring to a leaking state can be seen from the oscilloscope as shown in Figure 11. The time period from 0.25 to 1.25 seconds is the voltage signal of the photointerrupter under monitoring state. It means that most of the light cannot penetrate the absorbent material under monitoring state. However, the time period between 1.25 to 1.75 seconds is the voltage switching process. The voltage signal of the photointerrupter under monitoring state is converted into a voltage signal under leaking state. Namely after the leaking occurs, the absorbent material is slowly full of red ink due to the capillary action, so that it gradually becomes transparent. Thus, the light can gradually penetrate the absorbent material and therefore voltage signals received from the photointer-


Fig. 11. Voltage signal switching process of a photointerrupter from a monitoring state to a leaking state.

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Fig. 13. The received Bluetooth wireless signals on the monitoring computer showing leakage detected at 21:36:47.

rises at a moment of 21:36:47 as shown in Figure 13, which means a leakage is detected from the blood leakage detector. After carrying out several tests on the developed blood leakage monitoring system, the results indeed show that the realtime monitoring on the blood leakage detection during the hemodialysis therapy is achieved. IV. D ISCUSSIONS

Fig. 12.

Photograph of a blood leakage detector worn on a human arm.

rupter become higher. In addition, during the final time period from 1.75 to 2.25 seconds, it shows the voltage signal of the photointerrupter after leaking state. It means the absorbent material has completely become transparent, and thus, the voltage signal is gradually stabilized. In this study, the developed blood leakage monitoring system includes the blood leakage detector and the user interface software. The blood leakage detector is worn on a human arm under a simulated hemodialysis treatment as shown in Figure 12. It also connects to the user interface software installed on the monitoring computer, which actually combines the hardware and software to verify the effectiveness of the proposed blood leakage monitoring system. In this study, the developed blood leakage monitoring system is implemented to monitor the blood leakage conditions under a simulated hemodialysis treatment. In Figure 13, the user interface software installed on the monitoring computer shows a window screen of that the blood leakage under a monitoring state transforming to a leaking state. It is clearly seen that the blue line represents the received Bluetooth wireless signals sent from the blood leakage detector, and it is at the bottom from the beginning. However, it suddenly

In the early stage of this study, a laser diode is used as a sensing light source in the blood leakage detector and with the received variation of the voltage signals from the photo detector, blood leaking conditions can be determined. However, the laser diode requires a higher power input of a 9V battery. Thus, a very short battery life time is measured on the blood leakage detector due to the higher power consumption of the laser diode. After comparisons to other light sensing sources, this study adopted an infrared LED (Light Emitting Diode) in the detector due to its small size, larger beam size and can be powered by a typical 3V button battery. After a series of experimental verifications, the battery life time of the blood leakage detector still cannot reach the goal of this study (>4 hours). Moreover, two individual components, transmitter and receiver, are needed for using an infrared LED, which results in difficulty to standardize a sensing distance. Therefore, an infrared LED is neither an applicable light sensing device for our study. Finally, this study used a low power consumption and a fixed sensing distance light sensing device, a photointerrupter, to solve the problems encountered previously. The durability of the battery for the developed blood leakage detector is the major problem to overcome in this study. In the beginning, the electronic components, alert light and buzzer, were removed due to the insufficient battery life, and the power of the detector can only last for around 10 minutes. After replacing it with a SMD LED for the warning light and modifying parameters on the firmware, the power was increased to about 30 minutes. Finally, after the replacement of the Panasonic CR-123AEP battery, the developed blood leakage detector in this study has been able to continue to operate for more than 40 hours. Therefore, this study

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reinstalled the alert electronic components (SMD LED and buzzer) in the circuit of the detector in order to achieve the proper functions of the device. V. C ONCLUSION In this study, the developed blood leakage monitoring system is an independent system, and thus, it could be simply used along with the current hemodialysis equipment. In addition, it is a non-invasive monitoring device, which enables an easy installation of the detector on the human arm. The main feature of the developed blood leakage monitoring system is that once the blood leakage is detected, the alert sound and a warning light will be activated, and the alert signal will also be sent to a monitoring computer with the developed user interface software installed, such as a healthcare station, through Bluetooth 4.0 wireless transmission method. Thus, the relevant healthcare workers could give appropriate treatment immediately. In addition, a common toilet paper after trimming to a suitable size (40 × 10 mm) could be used as the absorbent material for the capillary action, and therefore, reducing the cost of the sensing expendables. Last, test results show that the blood leakage detector only requires a very small amount of red ink (0.01 ml) and takes just 1.6 seconds to detect a leaking condition, which produces a fast monitoring system on the hemodialysis therapy. ACKNOWLEDGMENTS The authors would like to express their appreciation to the Mackay Memorial Hospital, Taipei, Taiwan, for providing the facilities support for this study.

Ho-Chiao Chuang received the B.S. degree in mechanical engineering from Dayeh University, Changhua, Taiwan, in 2000, and the M.S. degree from the Department of Power Mechanical Engineering, National Tsinghua University, Beijing, Taiwan, in 2002. He joined the Professor Victor Bright’s MEMS Group in 2004, and received the Ph.D. degree from the Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, CO, USA, in 2008. He has been an Associate Professor of Mechanical Engineering with the National Taipei University of Technology, Taipei, Taiwan, since 2013. His current research interests include the fabrication of through-silicon-via (TSV) for 3-D IC, ultrahigh aspect ratio of the TSV using the supercritical CO2 electroplating process, and the development of new biomedical instruments, in particular, the aspect of counteraction treatment couch for respiration induced tumor motion.

Chen-Yu Shih received the B.S. degree in mechanical engineering and the M.S. degree from the National Taipei University of Technology, Taipei, Taiwan, in 2011 and 2014, respectively, where is currently a Research Assistant with the Department of Mechanical Engineering. His research is focused on the development of a blood leakage monitoring system for the applications in hemodialysis therapy.

Chin-Hui Chou received the B.S. degree in electronics engineering from the Oriental Institute of Technology, Taipei, Taiwan, in 2012, and the M.S. degree from the Department of Mechanical Engineering, National Taipei University of Technology, Taipei, in 2014, where he is currently a Research Assistant. His research is focused on the development of a blood leakage monitoring system for the applications in hemodialysis therapy.

R EFERENCES [1] 2013 Annual Data Report, USRDS, Ann Arbor, MI, USA, 2013. [2] I. D. Maya and M. Allon, “Vascular access: Core curriculum 2008,” Amer. J. Kidney Diseases, vol. 51, no. 4, pp. 702–708, 2008. [3] B. Axley, J. Speranza-Reid, and H. Williams, “Venous needle dislodgement in patients on hemodialysis,” Nephrol. Nursing J., vol. 39, no. 6, pp. 435–445, 2012. [4] HEMOdialert—Home. [Online]. Available: http://www.hemodialert. com/, accessed Feb. 13, 2014. [5] A. E. Page, “Device and apparatus for detecting moisture,” U.S. Patent 8 144 021, Mar. 27, 2012. [6] Redsense. [Online]. Available: http://www.redsensemedical.com/ startpage.html/, accessed Feb. 13, 2014. [7] D. Engvall, “Blood leakage detection device,” U.S. Patent 20 080 249 487, Oct. 9, 2008. [8] J. Ahlmén, K. H. Gydell, H. Hadimeri, I. Hernandez, B. Rogland, and U. Strömbom, “A new safety device for hemodialysis,” Hemodialysis Int., vol. 12, no. 2, pp. 264–267, 2008. [9] R. Wariar, T. P. Hartranft, N. Cameron, A. Lasso, and H. Caro, “Needle dislodgement detection,” U.S. Patent 7 147 615, Dec. 12, 2006. [10] A. Lay-Ekuakille, G. Vendramin, and A. Trotta, “Robust spectral leak detection of complex pipelines using filter diagonalization method,” IEEE Sensors J., vol. 9, no. 11, pp. 1605–1614, Nov. 2009. [11] A. Lay-Ekuakille and P. Vergallo, “Decimated signal diagonalization method for improved spectral leak detection in pipelines,” IEEE Sensors J., vol. 14, no. 6, pp. 1741–1748, Jun. 2014. [12] Bluetooth Core Specifications 4.0, Bluetooth SIG, Washington, DC, USA, 2010. [13] CC2540 Data Sheet, Texas Instruments Inc., Dallas, TX, USA, 2013.

Jung-Tang Huang received the Degree from the Department of Mechanical Engineering, National Taipei University of Technology, Taipei, Taiwan, in 1981, the M.S. degree from the Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan, in 1986, and the Ph.D. degree from the Department of Mechanical and Aerospace Engineering, University of California at Los Angeles, Los Angeles, CA, USA, in 1992. He joined the Department of Mechanical Engineering, National Taipei University of Technology, in 1992. His research interests are broadly including the RF MEMS, CMOS-MEMS, CMOS-NEMS, and packaging technology.

Chih-Jen Wu received the M.D. degree from China Medical University, Taichung, Taiwan, in 1985, and the Ph.D. from the Department of Medical Sciences, Taipei Medical University, Taipei, Taiwan, in 2006. He has been an Associate Professor of Medicine with Mackay Memorial College, Taipei, since 2012, and an Attending Physician with the Division of Nephrology, Mackay Memorial Hospital and Medicine, Taipei, since 1992. His academic boards include Nephrology, Internal Medicine, and Molecular Medicine. His research interests are hemodialysis and protein bound uremic toxin.