# A Tunable Self-Offloading Module for Plantar Pressure Regulation in Diabetic Patients
## 1 Introduction  
Diabetes is a chronic disease of high concern; irrespective of age and gender, it has affected every section of society. As of 2021, over 529 million people have been affected by diabetes globally, which is projected to be 1.31 billion by 2050 [1]. Diabetes mellitus is related to several complications, such as diabetic retinopathy, nephropathy, and polyneuropathy, with a risk of foot ulceration [2], cardiovascular diseases [3], or some cancers [4]. The presence of peripheral sensorimotor neuropathy [5] among diabetic people is considered a potential contributor to foot ulceration (FU). Such foot pathogenesis not only reduces daily mobility, but may also stimulate worsening to the point of lower extremity amputation and, sometimes, death [6]. FU results in nearly 50% mortality within 5 years of its occurrence [7] and, therefore, requires immediate attention.With the growing number of cases of diabetes worldwide, it has become important to address this complex issue. There are a variety of practices [8; 9; 10; 11; 12] available to heal or treat FU. Though it is essential to pursue the best available treatment depending on the extent of the developed ulcer, on theother side, it is also useful to develop methods/tools to minimize the chances of FU among diabetic patients. With the use of thermometry [13], a personalized alert can effectively be communicated to pursue the necessary actions, but the continuous monitoring of the local state(s) of the foot may not be easy for every individual. There is a need for a tool that can make decisions to effectively limit/minimize the damage to foot skin. One of the key factors in the prevention of FU development is plantar pressure (PP) [14; 15; 16] reduction. The continuous monitoring and handling of PP requires its measurement and a feedback system to make some adjustments for its redistribution. One of the ways to gather feedback and make the necessary adjustments is based on involving patients themselves as decision-makers and/or observers, employing a suitable PP measuring/monitoring device [17; 18; 19; 20; 21; 22]. Based on the need and recommendation of a health consultant, removable or non-removable interventions [23] may be opted for. A non-removable knee-high offloading device [24] is generally considered to be more effective than other existing offloading practices. The said intervention has a low rate of acceptance or adherence by diabetic patients, and the user's perception and experience are, therefore, also of paramount importance. This has brought interest in extending research and development more into removable interventions. In this direction, the other possibility (not yet in medical practice) could be based on employing sensors and actuators with appropriate control mechanisms [25; 26]. With the online tracking of pressure and effectively bringing local changes, PP can be redistributed [27; 28]. Such an offloading technique is often referred to as active offloading, and the key advantage of such a method is the online accessibility of the local state(s) and, accordingly, enabling the control action for offloading. In our previous work [29], active-offloading-based intelligent footwear was presented, where pressure redistribution was conducted based on the activation/deactivation of the module(s) employing magnetorheological fluid-based valves. In contrast to the aforementioned advantages, there are some critical factors to consider when it comes to the daily usability of the said solution. In general, energy dependency, wiring complexity, and packaging affect the manufacturers, as well as the users. Depending on the sensing, actuation, and/or working principle, the overall device cost also becomes significantly high. This makes the discussed solution less affordable to diabetic patients, either in terms of their daily usability or financial affordability. A passive solution with the capability of PP redistribution within a defined safe limit may be an interesting alternative.