Colten - notably - the criteria you have created is a JSON object I believe - however - the criteria parameter that gets appended to the params ---- needs to be a string - so - you can either:
JSON.strigify your statement above or you can form a string query - much like the one I pulled from some working server code that I have moments ago...
var stimein15 = ThedateresultsofsomefunctioncallStringType();
var sQuery = "{'dutcsendnotification': {$lte : '" + stimein15 + "'}, 'snotificationstatus' : 'U' , 'sstatus' : 'U' }"
//console.log('Query for use against db for Notifications to be sent:' + sQuery);
params.criteria = sQuery;
hope that helps,
Bruce