Second Semester

Project Update 7: 4/18/17

Our final poster for the Senior Design Day presentation can be found here.

Recent Achievements: We have achieved physiologically relevant readings from each of our individual modules. The force sensor showed a dramatic spike in signal when impacted by a bullet fired at a range, our photoplethysmograph showed heart rate, our pressure sensor showed respiratory rate, our accelerometer was able to detect orientation and acceleration, and our extracorporeal blood sensor was able to detect a physiologically relevant glucose solution. These sensors have been integrated into a pouch, which serves as the primary protective housing for our system. Communications from Bluetooth to Matlab for data processing in our proprietary algorithm have been achieved. Furthermore, Matlab is capable of sending a live update to a webpage, which displays our data in a graphical format in real time. The website can be found here. We are in the final stages of integration testing and integrating the pouch itself into the ballistic vest. We have also ordered and plan to test a PCB with some of our sensory components built in.

Future Work: Senior Design Day will be held Monday, April 24, 2017, in the Student Life Center at Vanderbilt University from 3-6pm. We will present our poster and a live demonstration of the H.E.R.M.E.S. system at that time. We hope to see you there!

Project Update 6: 4/7/17

A link to the project update can be found here.

Recent Achievements: Overall design considerations are underway. The pouch for the final product and case for the Arduino and bluetooth module has been constructed and a wire diagram has been prepared, allowing for ready construction of the pouch upon final component testing. Final testing of the force sensor for sensor range are being conducted Friday April 7th before beginning pouch integration. The algorithm for threat assessment is capable of integrating accelerometer, blood glucose, respiratory rate, heart rate, and force signals, with thresholds to be established based on integration of results from our recent force sensor test at the range as well as our tests tomorrow.

Problems: Construction of a series of glucose sensors according to our design will require precise considerations of the circuit design. In addition, we hope to heat seal our circuit in plastic using resources found at the Wond’ry, thus requiring a functional design before proceeding with integration.

Future Work: Work on system integration will continue. Grant proposal and poster presentation progress is also concurrently occurring. Considerations to translate data analysis results from a laptop to a web platform are being made, and we hope to translate many of the electronics found on a breadboard to a PCB.

Oral Presentation 5: 3/29/17

A link to the project presentation can be found here.

Project Update 5: 3/17/17

A link to the project update can be found here.

Recent Achievements: Overall design considerations are underway with respect to the pouch material, integration of sensors, and organization of components. In addition to how the product itself will be integrated into the vest, we are working on physically integrating individual sensors into the design. The algorithm for threat assessment is capable of integrating accelerometer, blood glucose, and respiratory rate signals, with upcoming integration of heart rate and force detection. Force detection sensors were formulated into a circuit, and the photoplethysmograph is providing validated heart rate data, with blood oxygenation upcoming. The blood glucose sensor has also demonstrated over a month of lifetime.

Problems: Organization of the force sensors, which are quite small, will require use of mathematical analysis using time delay of arrival. We are currently in the process of meeting  with  professors  to  discern  what  needs  to  be  done. Integration of the plethysmograph into a sleeve-based module presents unique challenges that will have to be addressed, focused on ability to detect heart rate and consistency of data.

Oral Presentation 4: 3/15/17

A link to the project presentation can be found here.

Project Update 4: 3/3/17

A link to the project update can be found here.

Recent Achievements: Building on integration of multiple sensors, considerations were made on pouch construction. In addition to placement, orientation and attachment of the device to the vest, the pressure conductive sheet used for respiratory rate was transferred from proof-of-concept to a design ready for integration upon arrival of ordered parts. A 3-D sketch for housing the Arduino, power supply, and accelerometer was also prepared. In addition, preliminary proof of concept of the plethysmograph was established. Alert mechanisms (texting, email) from Matlab have been demonstrated, building on previously undertaken algorithm efforts.

Problems: Layering of the pressure-conductive sheeting for force transduction has proved insufficient and efforts have begun to utilize piezo films. Due to cost, preliminary efforts on writing a force triangulation algorithm will be necessary from small piezo sensors. The code for plethysmograph will also need to be simplified and processed.

Future Work: Work on the accelerometer, pouch design, and plethysmograph will continue. Once they arrive, piezo sensors will also be explored as a substitute for the force transduction module.

Oral Presentation 3: 2/22/17

A link to the project presentation can be found here.

Project Update 3: 2/17/17

A link to the project update can be found here.

Recent Achievements: We established preliminary proof of concept of accelerometer testing in the X,Y, and Z directions through voltage outputs in order to detect officer acceleration and orientation. In addition, using a two electrode electrochemical cell, we validated our extracorporeal blood sensor and obtained preliminary results. Briefly, one electrode was coated in glucose oxidase enzyme, a physiologically relevant concentration of glucose was placed on both electrodes, and a measurable current was obtained as the reaction proceeded. Layering of pressure-conductive sheeting was also begun to expand detection range. Finally, we began work on the housing material for our finished product, and demonstrated proof of concept for email/text notifications through Matlab.

Problems: Due to the small size of the plethysmograph, a breakout board has been ordered, effectively halting progress of this particular module. Layering of the pressure-conductive sheeting may prove insufficient and may warrant exploration of alternative pressure detection methods, primarily, piezo films.

Future Work: Work on the accelerometer and blood glucose sensor modules will continue. Prototyping for the expanded detection range of the pressure transducer, Bluetooth-enabled processing using Matlab, and physiologically relevant metrics for algorithm thresholding will continue to be explored as well.

Oral Presentation 2: 2/8/17

A link to the project presentation can be found here.

Project Update 2: 2/3/17

A link to the project update can be found here.

Overview:

Recent Achievements: We ordered and received extra Arduino boards, accelerometer, plethysmograph. We also put in orders for force transduction prototypes. Having extra Arduino boards allows us to work on separate facets of the project in a more high-throughput manner. Following last week’s demonstrated proof-of-concept utilizing the pressure-conductive sheet to sense respiratory rate, we implemented a successful filtering algorithm to smooth our respiratory rate data for more accurate readings. We also began conceptual design of an overall algorithm, focusing on thresholding levels.

Problems: Two-way communications between Bluetooth module and Matlab is proving difficult. We are also uncertain about the detection range of the pressure-conductive sheet; experiments are being designed to test this. Also, the plethysmograph module itself is smaller than anticipated; soldering it will likely be difficult.

Future Work: Work on plethysmograph and accelerometer modules will be initiated. Prototyping for the pressure transducer will also continue, as well as further exploration and troubleshooting of Bluetooth capabilities.

Oral Presentation 1: 1/25/17

A link to the project presentation can be found here.

Project Update 1: 1/20/17

A link to the project update can be found here.

Overview:

Recent Achievements: We ordered and received Velostat pressure-conductive sheets, an Arduino Uno, and a compatible HC-05 Bluetooth module. We demonstrated proof-of-concept utilizing the pressure-conductive sheet to sense respiratory rate.  Digital filtering is necessary. Also, other materials for different modules have been ordered.

Problems: Preliminary testing of the HC-05 Bluetooth module suggests it is not robust enough to meet our signal transmitting needs. We are looking into alternative modules.

Future Work: Considerations regarding lead placement and conductive material surrounding the Velostat material will be explored. Preliminary efforts to obtain duplicate data streams for simultaneous digital filtering for respiratory rate and external forces will be considered. Bluetooth communication capabilities will also be tested.

 

First Semester

Oral Presentation 11/14/16

This presentation was a summary of our current progress as well as an overview of the BME Idea Grant Application being prepared by the team due in Mid April 2017.

Project Update 1: 11/3/2016

Project Overview:

Conceptual Developments:

Our team, in collaboration with our sponsors, determined a number of key biometric measurements that were deemed important for further exploration.

Monitoring heart rate remains the most important biometric marker in assessing the officer’s condition. Heart rate increases or decreases may be associated with life-threatening, high-stress and potentially dangerous situations, including physical confrontations, shock, or cardiac arrest. As such, upper and lower thresholds must be established in order to ascertain the circumstances experienced by the officer.  Resting heart rates for healthy adults are between 60-100 bpm. Sustained heart rates above this range or a rapid drop below this range are critical.

Blood oxygenation is another biometric measure of critical importance in assessing an officer’s condition. Sever hypoxemia as a result of inadequate oxygen saturation of hemoglobin – the carrier of oxygen on red blood cells in systemic circulation – can cause organ failure and may lead to cardiac arrest. Blood oxygenation below 80% is critically low and warrants immediate medical attention.

Respiratory Rate(RR) is another important biomarker in assessing the condition of the officer. There are two primary ways that RR can be used to determine the condition of the officer. The first is simply the RR value itself and the second is a measure of the erratic nature of breathing. A typical RR is around 12 – 20 breathes pre minute and any significant increase to this number is cause for concern.

Detecting the presence of blood is another critical component in determining the severity of a situation. Wounds from a knife, gunshot, or blunt object can cause hemorrhaging leading to significant blood loss and even death. This is particularly important if the officer is alone, as it provides information crucial to first responders and secondary units. Therefore, a system that can detect the presence of extracorporeal blood and notify the virtual partner is necessary.

Tracking the officer’s orientation and acceleration will also be crucial for quick detection of vehicle-related incidents. If an officer is struck by a car or is involved in an accident while in their vehicle, they will likely be knocked unconscious, left unable to call for help. A system, then, should be put in place which determines when an officer’s orientation changes rapidly or when they experience significant g-force.  This information will also be communicated to the virtual partner system.

Integration:

In order to consolidate and make sense of the information obtained by the sensors, an analytical algorithm is necessary. Specifically, both a baseline and emergency thresholds must be set for each officer. The algorithm will then detect when certain biometrics or force parameters have reached emergency thresholds and, when appropriate, trigger communications with a virtual partner. A communication method will be established that complements existing officer protocol.

 

Technical Decisions:

Heart Rate/Blood Oxygenation:

Methods to reliably detect heart rate were first considered. Two primary strategies were considered: contact and non-contact methods. In exploring non-contact methods in literature, there was a notable lack of reliable and durable approaches that could be integrated into the protocol of police officers. Primary methods relied on using light to monitor locations on the forehead or behind the ear. However, neither of these approaches provide monitoring in the least-disruptive way possible, and ultimately did not meet the needs outlined by the project sponsor.

We turned then to contact methods to monitor heart rate. Two primary methods emerged as the most viable for heart rate monitoring: one-lead ECG and photoplethysmography. The former is a recognized clinical and well-studied device. Utilizing the characteristics electrical activity of the heart, it is possible to discern heart rate, most commonly using the relatively large voltage spikes associated with ventricular depolarization in the QRS complex. The latter technology is relatively novel, but is now ubiquitously found in a number of technologies, most commonly Fitbits. Photoplethysymography also offers the unique advantage of easily integrating blood oxygenation into the device. Initial exploration will thus utilize light to determine heart rate as well as blood oxygenation. However, integration into the vest in a simple and convenient fashion remains a fundamental challenge.

Respiratory Rate:

There were two detection methods examined for detection of respiratory rate: microphone detection and volume detection. It was determined that in order to use this method of detection the existing microphone must be used to reduce the daily burden on the officer. This was less than ideal so the decision was made to switch to volume detection. This is made much simpler because a vest is already being used therefore simply detecting the force exerted on the inside of the vest will be indicative of the change of volume of the chest. In order to detect this, a layer of pressure sensitive material will be implemented along the interior of the vest to determine the force exerted by the chest on the vest and correlate this to a change in chest volume.

Blood Sensor

Methods of detecting and reporting the presence of blood were considered. A primary strategy was identified and researched in more detail. This method consists of a small system of electrodes which have been coated with an enzyme film. Specifically, this film is comprised of glucose oxidase enzyme, an electron transfer mediator, and a stabilizing agent(s) for longevity of the sensor. When exposed to glucose from the blood stream, electrodes detect the electric current generated from the enzymatic redox reaction, and send this signal to the virtual partner for notification.

Sensor Processing/Communications:

An Arduino Uno microcontroller will be used as the main processing component in the prototyping phase of development. This board makes it easy to integrate and process several inputs with the use of a plug-and-configure method. Moreover, it provides user-friendly software and the team has experience working with the platform.

Two possible technologies for communication were considered: Bluetooth and RF. Bluetooth would work over the officer’s mobile device and RF would work over existing police radios. It was decided that Bluetooth was within the scope of the budget and time allotted for the project and was most compatible with Arduino. Specifically, the HC-05 Bluetooth module will be tested as the main method for communicating with iOS and Android devices.