Richard Ribon Fletcher

Massachusetts Institute of Technology, Cambridge, MA, United States

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Publications (8)1.69 Total impact

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    Richard Ribon Fletcher, Ken-Ichi Amemori, Matthew Goodwin, Ann M Graybiel
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    ABSTRACT: A portable system has been designed to enable remote monitoring of autonomic nervous system output in non-human primates for the purpose of studying neural function related to social behavior over extended periods of time in an ambulatory setting. In contrast to prior systems which only measure heart activity, are restricted to a constrained laboratory setting, or require surgical attachment, our system is comprised of a multi-sensor self-contained wearable vest that can easily be transferred from one subject to another. The vest contains a small detachable low-power electronic sensor module for measuring electrodermal activity (EDA), electrocardiography (ECG), 3-axis acceleration, and temperature. The wireless transmission is implemented using a standard Bluetooth protocol and a mobile phone, which enables freedom of movement for the researcher as well as for the test subject. A custom Android software application was created on the mobile phone for viewing and recording live data as well as creating annotations. Data from up to seven monkeys can be recorded simultaneously using the mobile phone, with the option of real-time upload to a remote web server. Sample data are presented from two rhesus macaque monkeys showing stimulus-induced response in the laboratory as well as long-term ambulatory data collected in a large monkey cage. This system enables new possibilities for studying underlying mechanisms between autonomic brain function and social behavior with connection to human research in areas such as autism, substance abuse, and mood disorders.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2012; 2012:4046-9.
  • Richard Rib√≥n Fletcher, Sharon Tam, Olufemi Omojola, Richard Redemske, Joyce Kwan
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    ABSTRACT: We present a wearable sensor platform designed for monitoring and studying autonomic nervous system (ANS) activity for the purpose of mental health treatment and interventions. The mobile sensor system consists of a sensor band worn on the ankle that continuously monitors electrodermal activity (EDA), 3-axis acceleration, and temperature. A custom-designed ECG heart monitor worn on the chest is also used as an optional part of the system. The EDA signal from the ankle bands provides a measure sympathetic nervous system activity and used to detect arousal events. The optional ECG data can be used to improve the sensor classification algorithm and provide a measure of emotional "valence." Both types of sensor bands contain a Bluetooth radio that enables communication with the patient's mobile phone. When a specific arousal event is detected, the phone automatically presents therapeutic and empathetic messages to the patient in the tradition of Cognitive Behavioral Therapy (CBT). As an example of clinical use, we describe how the system is currently being used in an ongoing study for patients with drug-addiction and post-traumatic stress disorder (PTSD).
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:1802-5.
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    ABSTRACT: We present a mobile system for cognitive b ehavioral therapy (CBT) developed for an ongoing study for patients with drug-addiction and post-traumatic stress disorder (PTSD). The mobile platform consists of two parts: a wearable sensor system for collecting algorithm training data in the lab, and a mobile phone application used to deliver therapeutic interventions as triggered by real-time sensor data. Ecological momentary assessments (EMA) are also used as a means of collecting subjective data and validating the sensor classification algorithm. We provide a brief description of the wearable sensors, mobile phone software and network architecture used in the study.
    5th International Conference on Pervasive Computing Technologies for Healthcare, PervasiveHealth 2011, Dublin, Ireland, May 23-26, 2011; 01/2011
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    ABSTRACT: Beneficial advances in the treatment of substance abuse and compliance with medical therapies, including HAART, are possible with new mobile technologies related to personal physiological sensing and computational methods. When incorporated into mobile platforms that allow for ubiquitous computing, these technologies have great potential for extending the reach of behavioral interventions from clinical settings where they are learned into natural environments.
    Journal of medical toxicology: official journal of the American College of Medical Toxicology 06/2010; 6(2):212-6.
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    ABSTRACT: Widespread use of affective sensing in healthcare applications has been limited due to several practical factors, such as lack of comfortable wearable sensors, lack of wireless standards, and lack of low-power affordable hardware. In this paper, we present a new low-cost, low-power wireless sensor platform implemented using the IEEE 802.15.4 wireless standard, and describe the design of compact wearable sensors for long-term measurement of electrodermal activity, temperature, motor activity, and photoplethysmography. We also illustrate the use of this new technology for continuous long-term monitoring of autonomic nervous system and motion data from active infants, children, and adults. We describe several new applications enabled by this system, discuss two specific wearable designs for the wrist and foot, and present sample data.
    IEEE transactions on information technology in biomedicine: a publication of the IEEE Engineering in Medicine and Biology Society 03/2010; 14(2):215-23. · 1.69 Impact Factor
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    Richard R Fletcher, Ming-Zher Poh, Hoda Eydgahi
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    ABSTRACT: Wearable sensors enable long-term continuous physiological monitoring, which is important for the treatment and management of many chronic illnesses, neurological disorders, and mental health issues. Examples include: diabetes, autism spectrum disorder (ASD), depression, drug addition, and anxiety disorders. In this paper, we present a few mobile health technologies developed by our group and also discuss emerging opportunities as well as existing challenges. Technologies presented include wearable sensors for electrodermal activity (EDA) and mobile plethysmography as well as mobile phones and the supporting wireless network architecture.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:1763-6.
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    Richard R Fletcher, Sarang Kulkarni
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    ABSTRACT: We present a new type of non-contact sensor for use in ambulatory cardiac monitoring. The sensor operation is based on a microwave Doppler technique; however, instead of detecting the heart activity from a distance, the sensor is placed on the patient's chest over the clothing. The microwave sensor directly measures heart movement rather than electrical activity, and is thus complementary to ECG. The primary advantages of the microwave sensor includes small size, light weight, low power, low-cost, and the ability to operate through clothing. We present a sample sensor design that incorporates a 2.4 GHz Doppler circuit, integrated microstrip patch antenna, and microntroller with 12-bit ADC data sampling. The prototype sensor also includes a wireless data link for sending data to a remote PC or mobile phone. Sample data is shown for several subjects and compared to data from a commercial portable ECG device. Data collected from the microwave sensor exhibits a significant amount of features, indicating possible use as a tool for monitoring heart mechanics and detection of abnormalities such as fibrillation and akinesia.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:365-9.
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    ABSTRACT: Background: The autonomic nervous system (ANS) is a control system in the body with far-reaching influences, including maintenance of heart rate, digestion, respiration rate, perspiration, discharge of urine, shifting of attention, signaling of anticipation and salience, biasing of memory, and more. The autism literature includes many measures of ANS activity, showing, for example, that both skin conductance and heart rate responses in children and adults on the spectrum are generally increased or decreased compared to non-autistic controls. However, these studies have been limited to short intervals of measurement in research laboratories because the sensors are cumbersome, wired to medical devices, subject to motion artifacts, or prohibitively expensive. Objectives: To develop low-cost tools enabling comfortable, wireless, ultra-dense accurate measurement and communication of in-situ ANS data for people on the autism spectrum while they go about natural activities. Methods: We are constructing a wrist-worn wireless device that includes skin conductance, motion, and heart-rate sensing. We tested the skin conductance portion in four individuals with high-functioning autism while they engaged in a conversation with familiar teachers in a school and with one non-verbal 6-year-old diagnosed with autism for several days and nights of typical activity. We are evaluating comfort, ease of use, motion artifacts, and validity of data. Results: All the participants tolerated wearing the device. We observed minimal motion artifacts. Concomitant analyses of skin conductance and conversational topic preferences revealed sensitivity to changes in arousability. Data capture from the non-verbal child showed skin conductance patterns during rocking, flapping, seizures, and sleep. We will present this data graphically with annotations, together with a live demonstration of the new technology. Conclusions: We have the first working pieces of a low-cost, comfortable toolkit that will enable autism researchers and people on the spectrum to begin to characterize and communicate continuous ANS activity in natural environments.
    International Meeting for Autism Research 2008; 05/2008