An ostomy is created in response to a gastrointestinal injury or disease, such as Ulcerative Colitis, Crohn’s disease and cancer. A stoma is created by a surgical opening in the lower abdomen, which allows for a section of the intestine to be brought to the surface to allow for the excretion of waste products. The resulting effluent is collected through an ostomy pouch that is attached to the abdomen via an adhesive skin wafer (baseplate) as indicated in Figure 1A. In recent years there has been a tremendous effort expended in the design and development of ostomy appliances, which has helped to revolutionize stoma care and management. However, despite the numerous advances, peristomal skin damage remains an issue and arises as a consequence of the gradual erosion of the protective skin wafer. This results in the underlying skin being exposed to the caustic ileostomy fluid (Figure 1B) which subsequently compromises the integrity of the skin barrier and inevitably leads to irritation and ulceration. In the USA alone, it is estimated that one million patients deal with the routine care of an ostomy, and at some stage they are likely to have experienced an incidence of peristomal skin complication (PSC). Although, there have been improvements in the development of materials used within ostomy appliances, there has been little technological innovation in regards to the active prevention of PSCs.

A novel skin wafer containing a printed electrode array has been designed which can permit the monitoring of the skin pH in situ and thereby alert the patient when the baseplate has been compromised (Figure 1B). The system is based on a conductive carbon layer which has been modified with a range of peptide agents to confer pH selectivity. This electrode layer is integrated within a hydrocolloid (carboxymethylcelluose based gel) which provides a protective layer from the effluent debris that would otherwise compromise the operation of the sensor. As the skin becomes compromised, the pH can be expected to increase and at this point the patient can be alerted to the situation and the pouch appliance replaced before the onset of a PSC. The design and construction of the skin wafer is described and its operation in ileostomy fluid is critically assessed.