What is artificial endocrine pancreas? Mechanism and history

Figure 3 Mathematical model for insulin infusion algorithm. The stepwise input of glucose concentration [X (t)] and biphasic response of insulin secretion [I (t)] are depicted. The relationship between input and output is expressed in the transfer function. I (s), X (s) and dX (s) are the Laplace transformed form of I (t), X (t) and dX (t)/dt, respectively. T₁ and T₂ are the first order delay in response.