Disposable Insulin Delivery System Mid semester report BME 200 300 Team Members Cullen Rotroff Leader Tyler Allee BSAC Kailey Feyereisen Communicator Malini Soundarrajan BWIG Client Michael J MacDonald M D Head Pediatrics Diabetes and Endocrinology Division Director Children s Diabetes Center UW Hospital and Clinics Advisor Professor William L Murphy PhD Department of Biomedical Engineering Abstract Doctor Michael J MacDonald specializes in type I juvenile onset diabetes A great deal of time money and research is invested into insulin delivery for insulin dependant diabetics While extremely intricate systems like Medtronic s MiniMed can effectively interact with a patient s daily routine to provide a complex daily insulin diet these systems are extremely expensive Our goal is to develop a cheap disposable drug pump that will deliver the basal rate of insulin for at least eight hours We developed three designs that could solve the problem and chose one design to pursue for prototyping and further research Our design will use hydrogels as an actuator and a valve to deliver constant increments of insulin If prototyping is feasible we believe we can develop this product for well under 100 00 a dramatic step down from the 6 195 MiniMed Paradigm Problem Statement Our objective is to design a novel method of drug delivery that is disposable small light and inexpensive The system must be comfortable and discrete while in use The product should utilize micro fluidics to deliver a constant flow rate between ten and fifty micro liters per hour with minimal error or fluctuation for no less than eight consecutive hours Introduction The human body uses a complex metabolic system to sustain life and power its everyday actions It converts complex forms of food into glucose a type of sugar Insulin a hormone secreted from beta cells of the pancreas convert glucose into more useable forms of energy If the body is in need of energy it aides the movement of glucose into cells for break down into useable energy forms Surplus glucose is then converted by insulin into glycogen for storage in liver muscle or fat cells Meanwhile glucagon released from alpha cells of the pancreas break glycogen down from the liver and release it into the blood stream between meals each day This homeostasis system can be seen in figure 1 Figure 1 Flow chart of insulin glucagon and glucose in the body http nema cap ed ac uk teaching odl odl5 insulin jpg Diabetes is a disease that disturbs the body s the body s use or production of insulin in the body This disease has three main forms Type I Type II and gestational diabetes Diabetes II is the most prominent form in the United States The problem occurs when muscle liver and fat cells develop an insulin resistance condition that inhibits glucose uptake into cells The pancreas responds by creating more insulin to compensate Over time the pancreas will become fatigued and will eventually lose the battle with insulin inefficiency Though it is possible to delay the development of diabetes II with a good diet and frequent exercise the pancreas will eventually fail to secrete enough insulin to adequately respond to glucose intake during meals A second less serious form of diabetes is gestational diabetes which develops temporarily in women in their late stages of pregnancy Though little is known about the causes of this diabetes type it is believed that developmental hormones from the mother s placenta also cause insulin resistance American Diabetes Association Our client Michael J MacDonald M D specializes in Type I diabetes Type I develops from an autoimmune response in which the body s white blood cells attack the insulin producing beta cells of the pancreas More than 700 000 children and young adults are affected each year Type I is most commonly developed in children which is why it is sometimes referred to as Juvenile onset Diabetes Type I is also called insulin dependant diabetes because the insulin producing beta cells are destroyed this type of diabetes necessitates treatment with insulin supplements Without the constant treatment of insulin blood glucose levels will become far too high which can have fatal repercussions for the diabetic Desirable glucose levels in a non diabetic human are between 70 and 120 milligrams per deciliter WebMD Inc These levels normally rise after meals but should return to normal a few hours after If insulin levels are too low glucose levels will remain over 180 mg dL Immediate responses include blurry vision frequent urination and nausea however there are many dangerous long term results of having consistently high levels of glucose High blood glucose levels cause blood vessels in the eyes to bleed which can result in blindness High glucose levels are hard on the kidneys and can eventually lead to kidney failure a loss that would require a transplant or use of a dialysis machine for survival High glucose levels can also result in nerve damage which would most notably be detected by pain or complete loss of feeling in the legs feet arms or hands Hyperglycemia can also lead to gum infections as well as infections of bones that hold the teeth in place Finally long term high glucose rates increase the risk of heart disease A type one diabetic must supplement the lacking insulin production of their destroyed beta cells with insulin injections Because insulin is a large protein it cannot be administered transdermally through the skin without the aid of ultrasonic frequency vibrations to further open the pores of the skin It can also not be administered via pills because the protein would be broken down by the acids and enzymes of the stomach Although a great deal of research is committed to discovering alternative methods of insulin delivery subcutaneous injection is the major method at this time Insulin is ideally injected subcutaneously into adipose tissue of the abdomen which requires 9 1 mmHg of pressure Injection location must be rotated to avoid hypertrophy a build up of scar tissue at the injection site A picture of where subcutaneous tissue is located is shown in figure 2 Figure 2 Picture of skin anatomy shows where the subcutaneous layer is http www engr utexas edu bme faculty schmidt Research TissEng img skindiagram jpg Insulin regulation can be broken down into two main components throughout the day the Bolus injection and the basal rate Typically a diabetic utilizes two different phases of insulin to handle the different components short
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